I can't speak fpr other brands, but the Standard/Blue Streak brand carb kits usually will cover all varients of a given carb model. They also include a guide of the numbers and where to find it on the carb so you can ID it. I don't think taht the Rochester B is too difficult to overhaul.
You may want to check around the manifold ports for vacuum leaks, and the line to the advance too. Could have a bad gasket.
By the way, what is that peice that is welded to the carb top?
