look at things seperately, you can keep everything 6V by just using a 6V coil on the later engine along with the 6V flywheel and starter and the 6V gen/reg - you can change to 12V and still keep the 6V starter or you can find a 12V starter from 55-59 that still uses the foot stomp .... the main consideration is really the gauges and accessories when going to 12V
Bill
