You guys got me curious, so I went and looked. The only thing the rulebook says about brakes is:
"6.1.2 All motorcycles must meet the following requirements in addition to the applicable requirements in Section 5.
A. Original equipment wheels, brake calipers, forks, frame, engine, fuel induction system, and swing arm must be used.
B. Aftermarket brake rotors may be used but must be the same dimensions as the originals and must be made of a ferrous material. Non-current motorcycles may use brake rotors up to the same size as those that come as original equipment on the current model machine."
which to me, in regular ccs rule fashion, means that it's legal for SS...