E-street vs Promaxx vs 440 Source

Stock heads can get you there easy enough . I had a 440 out of a New Yorker with maybe 9:1 compression , home ported 906s using MP templates and 2.14 intake valvles , small solid roller (.550ish) , 6 pack intake , 2" Hooker headers thru 2.5" exhaust out thru the tips, J-Convertor , Mopar electronic ignition ....
It was enough to push my 3950 lb 1970 Charger down the track at 12.30 @ 112 mph with 3.55 gears.

I also had a 440 (71 NYer bottom end) with a 284/484 purple stick and a TM7 with 906s in my 74 Shortbox 4x4 Powerwagon that would aniliate 33" tires thru 3.55s. It was unerving to drive in the rain with out going into 4WD . I yanked it and put it in my 65 Coronet 500 . It ran 12.90s with 3.91s.

I dont see why you would need aftermarket heads to break 500 horse.