You're still guessing at the numbers which is a bad sign. The math isn't difficult so you should sit down and figure out what gasket thickness you need to get to 10.5 compression. 0.040 or 0.050 isn't going to take you from 11.60 to 10.50.

You might be able to have Cometic build you a super thick gasket but once you do that you're going to have assembly problems. If you want that engine to run on pump gas you'll need to pull it apart and add a shallow dish to the pistons or open up the heads a bit.