You are going to be directed to the RJC head gaskets. I bet you can mill the heads down from 48cc to 46cc. I wouldn't go too much because the intake will need to be milled as well. More work than needed since you can simply turn up the boost! Now if you were to build a new short block you can order pistons to do this without all the milling.
Cometic will custom make you some .027" gaskets. Odds are they won't seal against your used unmachined deck though.
And like mentioned above, shaving the hell out of the heads and running thinner gaskets will require the intake to be milled too. The machine shop costs halfassing a stock shortblock will probably cost more than a set of new slugs.