factory 72 340 pistons???

Yes be sure to degree the cam. Mine had to be advanced like 8 degrees to get it @ 106 with my cloyes chain. The chains all vary a little so degreeing is very very important. My motor had 2.02 J heads with some gasket matching and some bowl porting and it made 398 HP with an LD340 and a holley 750. Very nice little motor. I just sold it 3 mo. ago and replaced it with my 428 aluminum headed 340. Guy put it in a 71 drop top cuda and loves the motor. I should have kept it, but unfortunately I cant afford to keep them all. Also keep in mind with planed heads you will need to run adjustable rockers or shim your rocker shafts.