Finally got my rebuild kit from the Carb Dr. today. Turned out to be a standard Walker 15323B. FLAPS originally said that they only had one kit for the B. Now they say they can get they 15323B, but they'd have to order it. Hmmmmmm They also had to order the one that didn't have the right parts.
My B is a 7205461, and the kits for the earlier models don't work because of the different accelerator pump connection.
The question is, though, what effect does a missing sphere have on a B? I found a great illustrated set of instructions for a B rebuild on line, and the second thing it talks about is removing the 'T' shaped retainer, the spring under it, and the metal sphere under that. It said to use the larger of the spheres that came with the kit to replace the existing one.
Retainer: check
Spring: check
Metal sphere: nope. None in the well.
What's that well for and what happens when the sphere isn't there? Carb came off of a 1962 Chevy 292(?), and is obviously not original. I didn't own the donor vehicle and don't know if it ever ran with this carb on it.