340 build

To clarify: The 10.49 number is with the .039" thick Felpro 1008.

Using the .051" thick Felpro 5883PT, I get 10.16 SCR. It also assumes the valve reliefs are actually 7.6 cc's volume.

I take these results to be close but not necessarily exact, but good enough for planning cams and predicting/planning overall performance. There are always variables in deck height an other things like as has been pointed out and you have measured.

Don't get hung up on .1 or .2 differences in CR computations; the cylinder pressure differences that result will be 1-3 psi. That's waaaay down in the noise for most builds. It would take a lot of precision machining to get under .1 variations in SCR, which does not make sense for you.