Help on 408 build

If you want to keep the same cam regardless if you leave the j heads or go with some alloys the chamber size is going to be the same so pistons are probably the best option.

If you are willing to change the cam for something bigger and do some alloy heads and slightly thicker gaskets you probably wont need to change pistons.

How available is e85 from the pump over there, could look at retuning it to suit and running it with a bit less timing?