I was able to ID the wheel after some email back and forth with a helpful rep at Michigan Wheel. It’s an M56 or SMC56 and does appear to be the correct general purpose wheel for this motor. Who knows where the other numbers came from. Job numbers at a prop shop?

MWC’s position is that the extra weight (polar moment, really) of bronze wheels was never a problem and it was only cost that killed bronze outboard props. I don’t feel entirely convinced….