I have a '72 F-100 with a360fe and aC6 tranny.I use to pull a 6X12 trailer with my racing kart.
I rebuilt the original 2150 carb and had a pro adjust it. It now stalls when I put it in gear, especially in reverse. when it's cold. I can't find any leaks and I put on an electronic choke.
The linkage jerry rigged and the mechanic suggested I get a new carb. When I rebuild the engine I want to make it a 390.
Should I get a new 2bbl or do you recommend a 4bbl. If so what model 2bbl or 4bbl and manifold combination would be best.

 

To maximize the swap to a 4V, first upgrade the exhaust with headers and dual 2.5-inch tubing through free-flowinig mufflers of your choice. You'll even feel the difference with a 2V because the stock manifolds are inherently restrictive.

When it's ready, swap to an Edelbrock Performer RPM and either an Edelbrock 1406 (or 1405) or a Holley 4150 or 4160. Stick with vacuum secondaries. "Double pumper" sounds good while bench racing but less kind MPG-wise.

A 2V upgade? I'd look into the 500 cfm Holleys (Summit PNs HLY-0-4412S or 4412C).