you won't be able to shave enough off to worry about that. You will run into valvetrain geometry issues long before you run into compression issues. With a stock cam, you should be able to take off around .030 without the intake valves hitting the pistons, but ideally, you should put some clay on top of the piston and roll it over and see what you actually have for valve to piston clearances before you cut anything. And do it with the acutal pistons and camshaft that you intend to use.
Mine, I took .050 off the head and another .050 off the block. Still runs on regular. But I need to take the spark plugs out to roll it over to set the valves. Can't turn it by hand with the plugs in. Runs great. No interference issues.
The Jalopy Journal
