carter, rochester, holley... The ones they use for the chebbys should work on your jimmy. You could probably get some type of adapter to run a 2bbl on the stock manifold. Do you have a 228, 248, 270 or 302.
I ran a 4bbl holley 390 on my 270 , new intake of course. It was a pretty staight forward swap. It gave me much better throttle responce. I didn't benefit from increased economy... foot got much heavier! Everything else was stock, and the engine had 250,000 miles when I installed it. It made it to 272,000 before I pulled it to overhaul. It still fired right up, but My rear main seal was gone and I was losing heaps of oil. I started feeling bad for the fish!
