"did you miss the part about TOWING AND DUALLY..
he'll gain nothing at the rpm he'll use his engine at.. other than a thinner wallet and LESS low end torque
I've built a fair share of engine and I have a pretty decent understanding about the math involed in acutally building and engine and not just assembling one!
Are you seriously going to try and tell me that a pair of larger oval port heads that are flowing 210cfm@ .300" and 265cfm@ .600" are going to out perform a set of aftermarket heads that have the same to smaller runner volume but yet are flowing 230cfm@ .300" and 340cfm@ .600". All the while the aftermarket heads will produce much better velocity across all lift ranges, there for creating better charge going into the cylinder on every intake stroke.
A set of decent aftermarket heads and 220-230° cam will produce more tq in a 489-496 from 1500-5000rpm all day long than one assembled with a set of 40+yr old gm castings with almost any cam that you put in there. An engine is an air pump, the more air you can cram in there the more power it will make. If a set of heads can produce far better flow and velocity at all lifts than another set of heads than the better flowing heads will produce more power at every rpm level, not just higher rpm. last time i checked, those valves open a full lift (from .000-.600" or what ever your max lift is) each and every time that cam makes a full rotation, it doesn't matter whether you are turning 600rpm or 6000rpm.
let me ask you as far as small blocks go, if you were trying to make as much tq as possible in the 2500-3500rpm range, do you think it would be better to use a set of 40+yr old double humps (that flow like crap, much like the factory oval ports compaired to todays standards) or a set of DART, EQ, RHS, Brodix, Canfield...180cc heasds which are going to produce better flow and better velocity from .100-.500"
I'm not telling this guy to go out and buy a set of 325-365cc intake runner heads here, I'm telling him to go with a modest 270-300cc intake runner head that has been designed in the past 10-15years.
Come on now, its basic math comprehension here.