The advantage of the 781's is in the breathing...the ports are quite a bit bigger than your peanut port heads. At lower to mid rpms, you probably wouldnt gain much...but at the upper end, they would flow much better. Bigger valves would be a good idea, maybe 2.19 intakes and 1.88 exhaust. That's what I did with mine. A little unshrouding and short side radius work and the 781's would be awesome. They are considered one of the best "as cast" big block heads out there as far as flow goes. (Im talking oval port heads) Hang onto them.