you put an oval port head on that motor and it will be done by 5000-5500 dont waste money on old 781 heads when you can get aluminum for a little bit more.

I see this is a little dated and not to argue but I have to add that the 781 oval port heads will in fact rev and build HP to 7000. I have a set of 781 with 2.19 in 1.88 ex small port work and milled to creat a 110 cc chamber on my 427. Not much material left after milling but these heads and flat tappet solid Isky cam helped to produce 423 RWHP at 6600 rpm in a 67 Camaro, Tremec TKO 600 and 9" rear.
From what I have read these heads work good until you reach the 650 HP mark and then need better heads.