Tips on selecting Pistons??

First thing I'd try to figure what cam range you'd be using and work backwards from there. And to figure that out gearing and powerband comes into play. 360 is a very capable engine usually don't have to go over 6000rpms to make huge power. Most probably peaking in the 5000-5500rpms (350-400 hp) with 260 to 280 cams. Once you figure out the cam not to hard to figure out CR needed.