I conveted the '46 59A in my '32 to 12 volts 45 years ago, by putting 12V fields in the '46 generator and installing a '57 Ford regulater.
Switched to 12V bulbs, and a 12V solenoid, the ammeter is a '29 Audurn, still use the stock '46 6V starter. After 45 years all compoents are still working fine. Granted it only gets used on Sunday afternoons in the summer. But Flatheads are forever.