When I rebuilt my GTX engine I used TRW forged pistons for a 71 440 4 barrel application and Felpro head gaskets. It runs fine on pump gas but does have a noticable power loss, does not pull hard on the big end.
65 Belvedere II Station Wagon 69 Coronet R/T convertible 70 GTX 70'cuda 99 Dodge Diesel dually 4X4