diff --git a/specs/gloas/fork-choice.md b/specs/gloas/fork-choice.md
index aeb091f9277..f526a5551ea 100644
--- a/specs/gloas/fork-choice.md
+++ b/specs/gloas/fork-choice.md
@@ -19,13 +19,14 @@
   - [Modified `get_forkchoice_store`](#modified-get_forkchoice_store)
   - [New `notify_ptc_messages`](#new-notify_ptc_messages)
   - [New `is_payload_verified`](#new-is_payload_verified)
-  - [New `is_payload_timely`](#new-is_payload_timely)
-  - [New `is_payload_data_available`](#new-is_payload_data_available)
+  - [New `payload_timeliness`](#new-payload_timeliness)
+  - [New `payload_data_availability`](#new-payload_data_availability)
   - [New `get_parent_payload_status`](#new-get_parent_payload_status)
   - [New `is_parent_node_full`](#new-is_parent_node_full)
   - [Modified `get_ancestor`](#modified-get_ancestor)
   - [Modified `get_checkpoint_block`](#modified-get_checkpoint_block)
   - [New `is_supporting_vote`](#new-is_supporting_vote)
+  - [New `should_build_on_full`](#new-should_build_on_full)
   - [New `should_extend_payload`](#new-should_extend_payload)
   - [New `get_payload_status_tiebreaker`](#new-get_payload_status_tiebreaker)
   - [New `should_apply_proposer_boost`](#new-should_apply_proposer_boost)
@@ -262,13 +263,14 @@ def is_payload_verified(store: Store, root: Root) -> bool:
     return root in store.payloads
 ```
 
-### New `is_payload_timely`
+### New `payload_timeliness`
 
 ```python
-def is_payload_timely(store: Store, root: Root) -> bool:
+def payload_timeliness(store: Store, root: Root, timely: bool) -> bool:
     """
     Return whether the execution payload for the beacon block with root ``root``
-    was voted as present by the PTC, and was locally determined to be available.
+    is considered ``timely`` (or not, when ``timely`` is ``False``), taking into
+    consideration local availability and PTC votes.
     """
     # The beacon block root must be known
     assert root in store.payload_timeliness_vote
@@ -276,19 +278,20 @@ def is_payload_timely(store: Store, root: Root) -> bool:
     # If the payload is not locally available, the payload
     # is not considered available regardless of the PTC vote
     if not is_payload_verified(store, root):
-        return False
+        return not timely
 
     votes = store.payload_timeliness_vote[root]
-    return sum(vote is True for vote in votes) > PAYLOAD_TIMELY_THRESHOLD
+    return sum(vote is timely for vote in votes) > PAYLOAD_TIMELY_THRESHOLD
 ```
 
-### New `is_payload_data_available`
+### New `payload_data_availability`
 
 ```python
-def is_payload_data_available(store: Store, root: Root) -> bool:
+def payload_data_availability(store: Store, root: Root, available: bool) -> bool:
     """
-    Return whether the blob data for the beacon block with root ``root``
-    was voted as present by the PTC, and was locally determined to be available.
+    Return whether the blob data for the beacon block with root ``root`` is
+    considered ``available`` (or not, when ``available`` is ``False``), taking into
+    consideration local availability and PTC votes.
     """
     # The beacon block root must be known
     assert root in store.payload_data_availability_vote
@@ -296,10 +299,10 @@ def is_payload_data_available(store: Store, root: Root) -> bool:
     # If the payload is not locally available, the blob data
     # is not considered available regardless of the PTC vote
     if not is_payload_verified(store, root):
-        return False
+        return not available
 
     votes = store.payload_data_availability_vote[root]
-    return sum(vote is True for vote in votes) > DATA_AVAILABILITY_TIMELY_THRESHOLD
+    return sum(vote is available for vote in votes) > DATA_AVAILABILITY_TIMELY_THRESHOLD
 ```
 
 ### New `get_parent_payload_status`
@@ -386,6 +389,21 @@ def is_supporting_vote(store: Store, node: ForkChoiceNode, message: LatestMessag
         )
 ```
 
+### New `should_build_on_full`
+
+*Note*: `should_build_on_full` is called by the proposer before deciding whether
+to build on top of the empty or full parent pending node. This function is
+similar to `should_extend_payload` but takes into consideration the PTC view on
+data availability.
+
+```python
+def should_build_on_full(store: Store, head: ForkChoiceNode) -> bool:
+    assert head.payload_status != PAYLOAD_STATUS_PENDING
+    if head.payload_status == PAYLOAD_STATUS_EMPTY:
+        return False
+    return not payload_data_availability(store, head.root, available=False)
+```
+
 ### New `should_extend_payload`
 
 *Note*: `should_extend_payload` decides whether to extend an available payload
@@ -400,8 +418,10 @@ def should_extend_payload(store: Store, root: Root) -> bool:
     if not is_payload_verified(store, root):
         return False
     proposer_root = store.proposer_boost_root
+    payload_is_timely = payload_timeliness(store, root, timely=True)
+    payload_data_is_available = payload_data_availability(store, root, available=True)
     return (
-        (is_payload_timely(store, root) and is_payload_data_available(store, root))
+        (payload_is_timely and payload_data_is_available)
         or proposer_root == Root()
         or store.blocks[proposer_root].parent_root != root
         or is_parent_node_full(store, store.blocks[proposer_root])
diff --git a/specs/gloas/validator.md b/specs/gloas/validator.md
index 49b690c2800..c5f7b574304 100644
--- a/specs/gloas/validator.md
+++ b/specs/gloas/validator.md
@@ -231,29 +231,34 @@ construct the `payload_attestations` field in `BeaconBlockBody`:
 ##### Parent execution requests
 
 The `parent_execution_requests` field contains the execution requests from the
-parent's execution payload. The proposer constructs this field as follows:
+parent's execution payload. Let `head = get_head(store)`. The proposer
+constructs this field as follows:
 
 - If the parent block is pre-Gloas (first Gloas block), set
   `parent_execution_requests` to an empty `ExecutionRequests()`.
-- If `should_extend_payload(store, block.parent_root)` is true (the proposer is
+- If `should_build_on_full(store, head)` returns `True` (the proposer is
   building on the parent's full payload), set `parent_execution_requests` to
-  `store.payloads[block.parent_root].execution_requests`.
+  `store.payloads[head.root].execution_requests`.
 - Otherwise (the proposer is building on the parent's empty variant), set
   `parent_execution_requests` to an empty `ExecutionRequests()`.
 
 ##### ExecutionPayload
 
-*Note*: `prepare_execution_payload` is modified in Gloas to take `store` as an
-additional parameter. It consults `should_extend_payload` to decide whether to
-build on the parent's full payload or its empty variant, selecting both the
-withdrawals source and the execution head for the new payload. When building on
-a full parent, `apply_parent_execution_payload` is called so that withdrawals
-are computed against the post-processing state.
+*Note*: `prepare_execution_payload` is modified in Gloas to take `store` and
+`head` as additional parameters. `head` is the return value of `get_head(store)`
+and must correspond to the parent that `state` was derived from. It consults
+`should_build_on_full(store, head)` to decide whether to build on the parent's
+full payload or its empty variant, selecting both the withdrawals source and the
+execution head for the new payload. When building on a full parent,
+`apply_parent_execution_payload` is called so that withdrawals are computed
+against the post-processing state.
 
 ```python
 def prepare_execution_payload(
     # [New in Gloas:EIP7732]
     store: Store,
+    # [New in Gloas:EIP7732]
+    head: ForkChoiceNode,
     state: BeaconState,
     safe_block_hash: Hash32,
     finalized_block_hash: Hash32,
@@ -262,9 +267,8 @@ def prepare_execution_payload(
 ) -> Optional[PayloadId]:
     # [New in Gloas:EIP7732]
     parent_bid = state.latest_execution_payload_bid
-    parent_root = hash_tree_root(state.latest_block_header)
-    if should_extend_payload(store, parent_root):
-        envelope = store.payloads[parent_root]
+    if should_build_on_full(store, head):
+        envelope = store.payloads[head.root]
         # Make a copy of the state to avoid mutability issues
         state = copy(state)
         # Apply parent payload before computing withdrawals
diff --git a/specs/heze/fork-choice.md b/specs/heze/fork-choice.md
index 91fe42c11a6..1277f17703b 100644
--- a/specs/heze/fork-choice.md
+++ b/specs/heze/fork-choice.md
@@ -225,8 +225,10 @@ def should_extend_payload(store: Store, root: Root) -> bool:
     if not is_payload_inclusion_list_satisfied(store, root):
         return False
     proposer_root = store.proposer_boost_root
+    payload_is_timely = payload_timeliness(store, root, timely=True)
+    payload_data_is_available = payload_data_availability(store, root, available=True)
     return (
-        (is_payload_timely(store, root) and is_payload_data_available(store, root))
+        (payload_is_timely and payload_data_is_available)
         or proposer_root == Root()
         or store.blocks[proposer_root].parent_root != root
         or is_parent_node_full(store, store.blocks[proposer_root])
diff --git a/specs/heze/validator.md b/specs/heze/validator.md
index 49f62cb2768..f7999b0e928 100644
--- a/specs/heze/validator.md
+++ b/specs/heze/validator.md
@@ -137,6 +137,7 @@ inclusion lists they have observed.
 ```python
 def prepare_execution_payload(
     store: Store,
+    head: ForkChoiceNode,
     state: BeaconState,
     safe_block_hash: Hash32,
     finalized_block_hash: Hash32,
@@ -144,9 +145,8 @@ def prepare_execution_payload(
     execution_engine: ExecutionEngine,
 ) -> Optional[PayloadId]:
     parent_bid = state.latest_execution_payload_bid
-    parent_root = hash_tree_root(state.latest_block_header)
-    if should_extend_payload(store, parent_root):
-        envelope = store.payloads[parent_root]
+    if should_build_on_full(store, head):
+        envelope = store.payloads[head.root]
         # Make a copy of the state to avoid mutability issues
         state = copy(state)
         # Apply parent payload before computing withdrawals
diff --git a/tests/core/pyspec/eth_consensus_specs/test/gloas/unittests/validator/test_prepare_execution_payload.py b/tests/core/pyspec/eth_consensus_specs/test/gloas/unittests/validator/test_prepare_execution_payload.py
index b40dc2285c9..3331df6e93f 100644
--- a/tests/core/pyspec/eth_consensus_specs/test/gloas/unittests/validator/test_prepare_execution_payload.py
+++ b/tests/core/pyspec/eth_consensus_specs/test/gloas/unittests/validator/test_prepare_execution_payload.py
@@ -144,6 +144,7 @@ def test_prepare_execution_payload__extend_payload(spec, state):
     parent_bid = proposal_state.latest_execution_payload_bid
     payload_id = spec.prepare_execution_payload(
         store=store,
+        head=spec.get_head(store),
         state=proposal_state,
         safe_block_hash=spec.Hash32(),
         finalized_block_hash=spec.Hash32(),
@@ -181,6 +182,7 @@ def test_prepare_execution_payload__no_payload_verified(spec, state):
     parent_bid = proposal_state.latest_execution_payload_bid
     payload_id = spec.prepare_execution_payload(
         store=store,
+        head=spec.get_head(store),
         state=proposal_state,
         safe_block_hash=spec.Hash32(),
         finalized_block_hash=spec.Hash32(),
@@ -204,6 +206,7 @@ def test_prepare_execution_payload__extend_payload_does_not_mutate_state(spec, s
     engine = CaptureEngine()
     spec.prepare_execution_payload(
         store=store,
+        head=spec.get_head(store),
         state=proposal_state,
         safe_block_hash=spec.Hash32(),
         finalized_block_hash=spec.Hash32(),
@@ -223,6 +226,7 @@ def test_prepare_execution_payload__payload_attributes(spec, state):
     engine = CaptureEngine()
     spec.prepare_execution_payload(
         store=store,
+        head=spec.get_head(store),
         state=proposal_state,
         safe_block_hash=spec.Hash32(),
         finalized_block_hash=spec.Hash32(),
@@ -253,6 +257,7 @@ def test_prepare_execution_payload__block_passes_state_transition(spec, state):
     engine = CaptureEngine()
     spec.prepare_execution_payload(
         store=store,
+        head=spec.get_head(store),
         state=proposal_state,
         safe_block_hash=spec.Hash32(),
         finalized_block_hash=spec.Hash32(),