The GTP rotor pack will work in the SC early or late model supercharger, just by changing the allignment dowels. The entire GTP supercharger will not work on an SC motor mainly because of the inlet configuration, but the snout and pulley mounting are also differint. People like the GTP rotor packs because they are coated rotors and in most cases are in better condition than an SC rotor pack, mainly because they are newer.
If you currently have an old style blower with bare rotors, the newer coated ones will fit tighter to the case and make a little more boost, so there can be some power increase. If you have a late model blower that already has coated rotors and is in good condition, you won't gain any power.