Marine 273 build

Ok, looks like I'm confusing people... I'll try to clarify.

My buddy and I are each looking at 273 builds. We're starting from the same point (200hp marine 4bbls with 8.5:1 CR and 675 heads). He is doing a full rebuild and going back together with the egge 10.5:1 pistons, ported 315's, the ld4 intake and the 340 reverse rotation cam.

My build isn't touching the short block, so keeping the stock pistons (which I presume are the 2bbl auto flat tops). Id love to get as close to the mid 9's CR as possible, and based on the numbers above I think I'd be close with a set of 302 heads. The cam will be the same 340 reverse rotation unless someone out there knows of something better that's available. Intake, I was thinking ld4b but am open to suggestions there as well.

Clear as mud? Ha.

Do my compression ratio numbers look correct for a stock 2bbl auto with 675 heads? I assume mine is the same... Just trying to get all the baseline numbers correct and then see the effect of the 302 chamber size once cleaned up, along with a thinner head gasket. I have not looked at any CR numbers for my buddy's build with the domed pistons and 315's.