318 budget build

Are you saying the advertised compression ratio of 9.2:1 with factory pistons and 302 heads is pretty close to what you measured/calculated out to 9.1:1?

That's good to know.
Even if the the pistons are .040" in the hole, it is 8.7 with those head gaskets and head chamber volume. And the .040" in the hole is not normal.. So I think this is 'optimistic' on the SCR; , mid-8's at best is more like it. I'd put in the .028" thick head gaskets if you can but not a deal killer.