How much difference in HP would be gained by replacing the 8.8 to 10.5 pistons? 8-10%??Been working on a 1965 2 barrel 273. It was a low miles (35K) original motor from a Dart. Rebuilt with original 8.8 pistons,rods. Honed cylinders not bored, crank polished.Heads redone.
Added the E4 isky cam...