I make outer bearing adapters for mounting '73 and newer C-body rotors on '73 and newer A/B/E/F/M/J/R body knuckles. They are no more likely to spin than the bearing itself.

You could also use '69-'72 C-body rotors, bearings and seals. These fit '72 and earlier B/E body knuckles out of the box.

If you install an A13 inner bearing and race, the earlier C-body rotors will fit '73 and newer A/B/E/F/M/J/R body knuckles without an adapter. I never looked into a seal for that combination, however.