My 518 C.I. low deck stroker(4.300 stroke x4.375 bore, Eddy RPM heads CNC ported by MCH, 10.29 to 1 comp. ratio pump gas motor)made 720 hp at 5800 rpm and 744 ft. lbs of torque at 4500 RPM, I change the intake to a Weiand Team G 4500 low deck and used a Wilson 2 inch reversion spacer with a 1050 Dominator carb that has really works well on all types of motors and that combination on its best pull made 708 hp at 5900 RPM and the same torque at the same RPM as the six pak I have since tested a higher compression 527 C.I. motor with Indy SR M.W. port size with two different Indy intake manifolds and the 4150 manifold(440-2) with a two inch tapered 4150 t0 4500 adapter made 22 more HP than the 4500 Indy intalke did with a one inch phenolic spacer and the same carb twenty minutes apart on a engine dyno. My point is maybe I should have had and tested a M1 4150 type intake with a tapered 4150 to 4500 adapter instaed of the 4500 intake on my 518 motor Bottom line is you have both intakes and both sets of carbs, I would try them both and keep the one on the car I liked the best and tell everybody else to kiss my rear bumper