318 Build - Expert Review Needed

Agreed. One also has to take into consideration the bore diameter of the gasket. Summits website has the compressed volume listed. At some point you are just splitting hairs. DODGE 5.2L/318 MOPAR SMALL BLOCK LA Head Gaskets
You know, now that you mention it, I can't remember that anyone ever measured a stock steel shim headgasket for bore size. I have no idea how big they were.