Arfelmcfarfel, From what I can tell, the "B" is a 235 carb and your truck probably came with a monojet either electric or manual choke. Maybe a PO swapped carbs on you. For an air cleaner, start looking at 235s. I'm pretty sure that most if not all were oil bath, but there are plenty of guys here that have converted them to paper element. You can always hit a pal with a lathe or a local job shop machine shop and have an adapter made. I'm looking for a 250 paper element air cleaner to cut up right now. I hope this gives you some ideas and doesn't muddy the waters!
Best wishes,
Les
