318 covid 19 build

The '68 318 factory pistons were supposedly much higher up in the bore than '71 or '72 and later smog 318's; I think George Jets has documented that info on this subforum. If correct, then your static compression ratio will be purty good with those Eddie heads like up around 9.3-9.4 with a Felpro 1008 head gasket, the closed chamber Eddie's (PN 60779) and pistons down around .005" below the deck. DCR would be in the high 7's with a 268-ish cam; darned good for a stock 318 bottom end.

Check the compression height on those early 318 pistons if out, or check how far they are down in the hole at TDC if still assembled. I hope you will be pleasantly surprised. Let us know what you find there.

I would not worry 1 second over the bigger breathing in and out parts if the compression is as I believe... the cam is going to control things.