Why use a crankcase breather filter? The point of the breather is that the crankshaft can vent. If their is any blow-by or the bike is run real hard and the engine foams, the filter will catch any oil and clog. The engine will stop running because gaskets and seals will blow. Most vintage bike guys (like myself), run a hose from the breather over the swingarm. The only possible downside is that if you live somewhere where mud-dobbers live, they can clog the hose.
What size pods are needed? I would recommend the cheap Emgo pods with paper elements. Paper filters are effective for a couple years unless you are in a real dusty environment. They are a lot cheaper and you just swap them out every season or two. The K&N or UNI filters need to be maintained; that is, washed and then oiled. Most folks are not consistent when oiling and this greatly effects the air fuel mixture. The CVK carbs on the BA are easy to tune; the pilot jets are the same type as used on the Vulcan with CVK carb or a Harley CV carb and the main jets are easy to source. There is no primary/secondary jet system as earlier Keihin CV carbs and it really isn't necessary to raise the jet needles; only bump the pilot jets a size (slow jets) and main jets need to be around #140 I would guess with pods. If you have no baffles in your mufflers, this requires a bit of adjustment as well and can create tuning issues (flat spots) that are hard to get rid of and require shimming the jet needles (washers are made specifically for this purpose for Keihin carb). The CVK carbs are actually pretty good choices and while throttle response is quite as perky as the Mikuni flat slide carbs I have seen, with proper tuning they will be more than up to the task.
