I am curious about these headbolt markings too.
I have WB bolts (fine thread) on my 9/30/68 Flint 327. Have spare AS and AT bolts (as well as WB). So would like to know correctness for those too.
Pic of WBs:
I have WB bolts (fine thread) on my 9/30/68 Flint 327. Have spare AS and AT bolts (as well as WB). So would like to know correctness for those too.
Pic of WBs:

Get a period Day 2 player and mount under dash next to console.