I think you had better do some research - I used to import Rocks and they all had AC synchronous motors, to which you could add the Merlin power supply.
The original arm would get sticky bearings, they are loose inside and there is a fix, but I'm not sure if I have the instructions any more. The sound improved significantly with the Merlin speed sontroller - more open, smoother, bigger soundstage. You might be better off putting the money into a speed controller.
The Rega arms were a popular combination with the TT. There was a paddle available to bolt onto other arms.