[Dan Bowles]

6V wiring can handle more because it is thicker wire. Follow the Stovebolt.com list and you'll be fine. Unless you are running HIDs or something stronger than the standard sealed beams, you don't need a relay.

You'll need all new bulbs and one reducer for the fuel gauge from my recollection to go with a new coil.

Starter and horn will continue to work on 12V but be louder and faster. As long as it is for limited use, they should both last a long time. You might want to look at the heater fan, though.