Hi Surfheadz
What engine are you running?
If it's a 30hp engine you'll need to get a porsche 12 volt generator.
30hp cast stands are smaller!
If not get a 12v dynamo (probably a new generator stand)
Change all the lightbulbs, change the coil,
If you have a later carb with autochoke you'll need to change
the heater(choke) element and the fuel cut off switc
You'll need a voltage dropper for the windscreen wipers,
If you have semaphores you'll need a droppper for these too,
Replace headlight and indicator relays.
You'll probably get away with the horn.
As for the starter i've run a bus 12 volts for 7 years using a 6volt starter and solenoid without any probs so far
cheers
Rich