You will need to change the generator, voltage regulator, and coil to 12v (and light bulbs and any other 6v devices/gauges). There is a
Tech Tip here about that change.
You will need a ballast resistor somewhere in the ignition circuitry before the coil (or, you will burn the points). You could use a 12v coil with built-in ballast resistor, but there are advantages of have an external ballast resistor and wiring the starting circuitry to all full 12v current while cranking/starting.
