Sleeving the hubs? Do any of the vendors sell such a sleeve? I know they sell a sleeve for the end of the trumpet but I don't recall seeing those.
Such a sleeve would have to be quite thin walled so little material has to be removed from the hub or, as Updraught suggests, the rollers would be smaller. I have a friend (who lurks on this forum and might chime in) who replaces the Ford bearing with modern roller bearings with great success. I've also seen ball bearings used but I don't like that idea because balls don't allow for end play in the shaft, which an axle will have.