My original crank pulley came apart into 3 pcs....lol My mechanic machine a solid one for me, still using after so many years.......I wouldn't change to a undersized crank pulley. In those days the only usable pulley was the mythelogy one because of the dampener it came with. I recommend you keep the stock pulley otherwise the engine will rev fast but the car doesn't move much. It's annoying.