Yo! I've got 30,000+ miles on the '76 Camaro I custom built with a 625 Carter AFB, 1" spacer, and 8004 Weiand manifold. Square to spreadbore. Works perfect and I get 15.5 mpg with a 350hp/411ftlb torque motor.
Why screw with perfection? So I built a nearly identical 350 ci motor for my 3/4 ton 4x4 '78 Chevy P/U,...Holley 600, 2" swirl squarebore adapter, and 8004 Weiand spreadbore intake.
Again, perfect!
We'll see what 6200 lbs and 4.11:1 rear gears does for the gas mileage in this truck! Todd.