A flat top piston with -5cc piston relief will give you 12:1 compression with the TF heads. That would make a nice race gas engine. Easy 700 hp combo with the TF heads and a healthy roller cam.

Diamond, ICON, Ross, Mahle and SRP all have a shelf piston that would work if you go with the 4.375 bore size.

Tons of people make a Chevy 6.535 long rod so just pick whatever works for your budget.