I'd say well over 700 hp is obtainable with bigger, less street friendly camshafts and aftermarket heads.
My 493" motor puts out a touch over 680hp at 5500 rpm with a very streetable .550" lift hyraulic cam.
Cab Burge has one that puts out more than mine.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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