OK, let's back up, you have a rebuilt 273 and you want a little more power? You came in the middle ofsomeones 318 thread and it gets a little confusing. I don't remember the specifics. Do you have a 2 barrel or 4 barrel? Single or dual exhaust. A 4 barrel , a nice set of duals, and recurving your distributor will do you more good than a half point of compression slightly larger valves and a voodoo cam.