C'mon, you guys!

Reed....carbs are made of aluminum or pot-cast. There isn't a great deal of strength required from them, as they aren't a structural component.
You'll have no luck with any type of welding or soldering to pot metal as the filler metal just won't stick to the parent material, which is high in zinc.
You can weld aluminum, but there is a pretty high risk of warping the parts that get heated up, and that will lead to leakage of either, (or both), vacuum or fuel.
The way I see it, your only hope for repair is JB Weld, and you'll have to go with the fuel safe stuff. Other than that, you'll have to find a different carb to salvage parts from.

Sorry, buddy.

Roger

Ugh. Well, I think I may have wasted my money on this carb. I cracked it open today to find that the float bowl is coated with rust and the secondaries are completely rusted tight. Add to that the bust choke parts and I think this carb is never going to run again. I guess I got a parts carb now. Bummer.