[morzh]

Got it, this darn Google.

Well, you could do a search on the motor you have, maybe even photograph and feed it to Google.

When you say "centrifugal regulator", what kind? Switch? Or the old style like those balls on steam engine that change the gear ratio, purely mechanical?
Synch, especially hysteresis, motor has no use for it, as any mechanical speed regulation would fight the rotating EM field. I am not sure how it would work.
The synch motors are used in Variable Speed drives where their speed is regulated by the field frequency. Regulating it mechanically is, well, kinda wrong.
If the motor runs a gearbox, where the regulator changes the gear ratio, then yes, that is quite possible.