dual plane vs single plane?

I think you could improve with a better dual plane. The M1 is not any better than a typical stocker, and i dont think as good as the iron '71 T quad factory intake. But it is lighter and prettier. The first single plane I'd use would be the M1 single, and I think it would be too soft low down for you. Dual planes have longer, smaller runners, and by the nature of the plenum divider help the low end carb signal. Dual planes usually have shorter, more direct paths, with larger cross sections, and larger plenum volumes to help maximize the mixture flow thru the carb/ports at WOT. Small tires, 3.55s, and a cam that will pull past 6K could use a better dual plane like the Air Gap.