as for the oil bath air cleaner it doesnt really matter what oil you use. just use the same as the engine and you cant go wrong.
wash it in kerosene. soak it and then slosh it up and down repeat a few times before rinsing it with fresh kero. let it drain well and reassemble only fill to the line on the bowl.

I got the oil filter apart it was stuck pretty good. It has a Napa 1169 cartridge inside. I looked at the cross reference for the 5B8934, and the Napa, or Wix # didn't come up. I've got other brands available.
The diagram of the filter doesn't show with that layout how the spring holds pressure on the arms to keep from turning. There originally was another latch that held the canister onto the base but I can see where it was broken and repaired, and broke again and not fixed. Possibly the Napa filter was a tighter spring fit....not sure, but if it leaks I may need to experiment.