After thinking about this, I pulled a 273 head off the shelf and unwrapped it. After looking at the witness marks from the .020 original head gaskets, I think any LA head gasket with 4.04 bore will work as well as anything. If one was to use a smaller bore the fire ring would not seal the combustion chamber of the head, even the 64-67 closed chamber head. Cometic makes a 4.04 bore with a .027 compressed thickness. I ordered 2 each and will see how they fit.
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