I finally got the wheel delivered a few moments ago, and rushed to put it on the new Rikon grinder.
Did a little twirl by hand (not under power) and noticed a far amount of run-out as the wheel spun.
I was under the impression the thing was machined flat over the surfaces, front and sides, so I wondered if that was normal. Of course I could be wrong, and only the face is machined flat but, I'm not sure.
The original wheel did not seem to "wobble" that way, so I don't think it's the shaft.