I had the same basic Q a couple of weeks ago ... and the cure-all(I think) .. is to get a set of copper head gaskets.

I have a 383 block that I am putting into a boat that will have 11 to 1 compression PLUS ... and the deck surface has some lite rust on it. I don't want to deck the block any further(don't want any more CR) ...so I think that the copper-gaskets will be the plan.