The 3.08:1 rear end is a highway gear, you want an engine that makes torque in the lower rpm range to be able to pull away from a stop easily. The 283 is a short stroke V8 and therefore makes its torque a little higher up the rpm band, I think the specs for a stock 283 had its peak horsepower at 4000 rpm and its peak torque around 2000 rpm. Anything you can do to make torque lower in the rpm band will help with drivability. The dual plane intake is designed for smooth power from idle to 4000 - 5000 rpm. The camshaft profile will play a large part in the idle, midrange, and high rpm characteristics of the power band. The intake manifold is inexpensive and pretty easy to replace and good bang for the buck. The one issue you are facing is that the Edelbrock carb is probably a square bore, the modern (1966 - 1986) small block factory manifolds are spread bore, they are designed for the Quadrajet 4 bbl. If you can locate a square bore manifold that will accept the Edelbrock without any adapters and not pay an arm and leg for it then that would be the easy way to go. The Edelbrock Performer manifold is perfect for your engine/carb/cam/headers, look for a used one on the normal e-markets. Look at the new price at Summit/Jegs/etc. then decide how much a used one is worth to you. $75 - $100 would be ok with me. I think it would help your truck quite a bit. I built a 355 years ago with the Edelbrock Performer cam and intake, ran the original Quadrajet, very predictable smooth power. That was in a 1984 Chevy 3/4 ton crew cab, I put 100,000 miles on that engine and it was happy.
