I've installed C-rotors on my '73 A-body spindles. I believe the outer bearing is the same on B-bodie spindles.
I made spindle bushings for the stock '73 C-rotor outer bearing to sit on.

The stock caliper brackets needed only 2 washers behind them to align the stock '73 C-body caliper to the rotor (Pin type).

I'm fairly sure the bracket for the Viper-calipers won't be that hard to align either.