Bendix RB2: splined cog?

[ParkRNDL]

I bought a junker bike for 20 bucks because it had a good working Bendix RB2 on it. My intent was to change the cog from a 20t to an 18 or 19t and use it on another project. Problem is, all the cogs I have are the type with the 3 locator nubs, not the internal splines like this one. I could just change the front sprocket to get the gearing I want, but I'm also a little concerned about the wear on this cog. Can anyone tell me more about this hub? Can I still find different cogs for it? From a quick search online, all I could find was a skiptooth cog.

 

[clamdigger]

So, it looks like the brake arms of the RB and the RB2 are interchangeable. You have a switch-a-roony. https://sheldonbrown.com/sutherland/CB-IGH-2-bendix.pdf

 

[ParkRNDL]

That's what I was thinking. And now I am looking at that diagram... hmmm...

I have an old gummed-up 28h Bendix 70 in the basement here. From that diagram, I wonder if I can take Part 15 and everything to the right of it from the 70 and swap it all onto the RB? Then I could look for a more readily available Bendix 3-lug sprocket with the tooth count I want...