I would go with the 4 barrel manifold. Cast iron ones are cheap ($20 at most, usually free) and most Chevy guys have a few laying around (I have 4 or 5). Your local salvage yard is a good place. While you're there, get an HEI distributor if you didn't swap already. You might want to find an air cleaner, too. Early 80's Chevy trucks are good bet. Don't forget to run a new wire from ign. switch to distributor. If you have points dist., the wire reduces voltage because it can't handle 12v. With HEI you can open spark plugs to .045". Your truck will start and run much better. All the parts you need will fit from any smallblock pre-'86.
