Max compression for pump gas iron head

Your lucky 302's are closed chambers so that helps. Shoot for zero decking the pistons and use a gasket that's .040-.045 thick. The cam also affects things. A long duration cam will bleed of cylinder pressure so you can run more compression. I'm running 9.9 to 1 compression on my 360 with open chambered X heads and a cam that's 234 degrees of duration at .050 and it never spark knocks on 93 gas with the total timing set at 34 degrees.

I'd say if you set it up like I described above you should be able to go 10.5 to 1 and be ok on 93. That's with a middle of the road performance cam.

If you polish the chambers real good and remove any sharp edges you might even get away with 11 to 1 comp.