I'll do it myself. I went online and found this website to get the formula and calculator for what the engine should be at, assuming the factory stock specs were right (0.141" piston in the hole, 3.4" bore, 0.020" gasket, 60cc chamber) .
RSR Static Compression Ratio Calculator It came out to 8.31 compression.
Then I found this calculator to figure the volume of a cylinder 0.060" high and 3.4" in diameter.
Volume of a Cylinder Calculator It showed 8.9 CCs.
A 0.060" DIFFERENCE (0.080" head cut and 0.020" thicker gasket) would remove 8.9 CCs from the combustion chamber.
Then I ran the first calculator with the new combustion chamber number of 51.1 CCs. I got an answer of 9.17.
Therefore the difference, again, the DIFFERENCE between 9.17 and 8.31 is 0.86 of a compression ratio.
That is what I was asking. Whatever my actual CR is, cutting the head 0.080 and using a 0.020 thicker gasket should make my CR 0.86 higher.
Now every /6 cylinder head I have either seen in person or online is an open chamber. The area that would be affected by milling up to about 80 or 100 thousandths is going to be a circle, unaffected by parts of the chamber shape. So I think my calculation is reasonably reliable.
Then to experiment a bit, I put in different numbers. Let's say my piston is 0.180" down and the head is 62 CCs. That is a 7.68 compression ratio. And then I ran the numbers with the head volume 8.9 CCs smaller (again, the volume reduction of a 0.060" head lowering), and I got 8.40 compression. With a resulting DIFFERENCE of (8.40-7.68) = 0.72 of a CR in change.