I really liked the -12.5cc dish, 1.32 CH piston that Diamond sells for the 400 with a 4.25" crank. Unfortunately the price has nearly doubled in ten years.

My current go to is Mahle and thankfully the 2023 catalog lists 1.320 CH offerings. The only dish piston I see listed is stock 440 CH.

Also of note is that Mahle makes a gas nitrided steel top ring that is sold only as a top ring package to go with the 2nd/oil ring provided in with the piston kits. This saves $100+ over buying a complete set of hellfire rings.

Here is the 2021 Mahle ( pronounced mah-la) offerings for mopars