just cc,d my heads will this be too much comp. ?

I ran my 340 .040 over .020 above deck with a fel pro 1008 .039 head gasket, [email protected] SFT 93 pump gas. I smoothed the chambers and piston valve relief edges, used autolite 65 plugs, and got the tune right. 24* initial 34* total mech, vac advance mid 40s. With a good gear and converter in a light car it's fine.
I now run the same motor with IMM Indy LAX closed chamber heads 63cc with a .060 SCE head gasket.