Putting 340 intake on 273 heads??

I thought I read that later 273 heads (66+) had less compression, so research that. There are alum intakes for the 64-65 heads, but rare now. I put an Edelbrock Performer on my 273 heads by counter-sinking the holes for a conical flat-head bolts which can **** to fit. Not ideal, but seems to work. Biggest concern is that the bolts have a small allen socket which could strip and require drilling the bolt heads off to remove the intake.