Compression ratio?

Trying to get an idea of my compression ratio but I am having troubles.

the engine is from a '76 Thunderbird, D0VE heads that have been machined .050". I am having a hard time finding specs for the 8265PT1 head gaskets though... Also, I know I can't get an exact number since I don't know exactly how far down my pistons are, or the exact CC of my combustion chambers etc...

using this quote

"The 97cc volume of the D3VE comes simply by dropping the chamber about .100" deeper into the cylinder head casting"

and the fact that D0VEs have a 76cc~ chamber, .100" more chamber created about a 21cc difference. So, .040 should make roughly a 10cc difference. Therefore, I would guess my machined heads to have around 66 CC chambers. switching from D3VEs to D0VEs will raise the compression about 1.5 points I am told. So, that would be about .07 points per CC of chamber.

D3VEs compression is roughly 8:1, raise that to 9.5:1 by putting the D0VEs on then another 10cc less chamber via the .040 shave and I am guessing right around 10.2:1...?

9.5-10:1 is pretty close