Starter will work on 12 volts, until you crank too long and it throws some solder, or the Bendix snaps. For $50 you can buy a rebuild 12v starter for a '63 Galaxy (FE engine) and swap the outside part with the field coils to your armature and ends.
Voltage reducer for heater and/or wiper motors.
Should also swap horn relay and starter solenoid to 12v equivalent parts.