Here's a Compression Calculator which could give you a few clues.

Yeah yeah yeah, Iknow... shoulda measured it and all that and the purists will have a field-day with this, but I was in a hurry and I'll figure it out this weekend at the racetrack but JUST CURIOUS what some of the experts on here's much-more-educated-than-mine's guess would be--I mean... roughly.

This head:



With about 100th taken off from that pic just for truing. (no markings, just H72 or whatever they all have. Not a GX head because it has stock valves, which were retained. But it had a much nicer quench pattern than some of my other heads, so went with it.)

A12 block 40 over.
A12 crank and rods.
40-over flattop pistons.

Was guessing it would be maybe 9.5 or so max, but just fired it up today and it's got a *pop* to it that makes me think it might be a bit higher.

Would rather anticipate fuel requirements rather than experience them this weekend at Buttonwillow.

All educated guesses will be mucho appreciated!