We put a Carter 400 CFM AFB on our shop van Foorrdd with 300 CID 6. Picked up a tremendous amount of power, and even better fuel economy. That one barrel was really choking down the engine.

Used the Offenhauser intake with heat. Had it on for several hundred thousand miles until the van rusted out the third time (I love Missouri salt and cinders in the winter - NOT).

The only mod to the carb was to ditch the electric choke, and hook up a manual choke. Much more reliable for vehicles that have to start in all kinds of weather.

Jon.

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop