Shawn, my knowledge is limited relative to many people on this forum. I tend to generalize the history of Pope and ABC. I like to think that while history paints him as a pioneer - and standardized threads are definitely a big help - I also think he was ruthless and used lawyers to absorb so many manufacturers, so he was a bully. I think that he threatened manufacturers until they joined him and sued them if they didn't. Since the bicycle was in decline and motors on the rise it was probably easy to absorb companies. Once he swallowed a company he just used the name or some other identifiable trait of the previous company. I think we all probably think that way about him (another generalization and assumption). I think that Keim was absorbed by Pope and your chainring was one of those interesting traits that he kept. I also question if that chainring was on your bike originally. Your frame could very well be early and the chainring just 5 years later. I'm just guessing here- Keim made frames for the jobbers so I would think he would be a target for Pope. I have two Keim frames and one of them has dropouts(rear fork ends) that seem to be a mix of Keim & Pope. The frame that I think is earlier has nicer dropouts than the other but they both have the same unique axle adjuster. The later frame also has the patented stamp on the BB shell but it says apr 25 9(?)3. the earlier one does not have this stamp. They also both have the Keim sun BB & chainring setup.
Sorry that was wordy and a bit of a divergence but I wanted to let you know why I was thinking that about your ring. That is one of my favorites and I thought about jumping on that bike when I saw it but I need to save space for some of my grail bikes if I can find them
Rick