'302' Combustion chamber volume?
You can have the heads shaved some to bring up the compression. I had a set of 302s shaved down to 57cc in which I used the thin Mopar Performance head gaskets which brought the compression up some more. I believe the compressed thinkness after mounting the heads is .020 ... anyways all said and done the compression of my motor is 10:7 it's a 360 by the way. I might later on install larger valves more than likely on the exhaust side and port them.