why are you converting the bike? lack of parts or other? I have done this on a DT250 and its a ton of work and you have to find a correct homemade Magneto for the positive system. The next bike I built was a Yamaha dt360 and I kept the 6 volt system. I was able to find 6 volt, H3 bulbs for the headlight on Ebay, they are the same as used in cars, very bright, long lasting. I used 6 volt LEDS for turns and brake lights. Thet are made by Harrison specialties on Ebay. Think about keeping it 6 volt. There are also single converters that you can hook one light on it, search Ebay for 6 volt converter, this will fix your headlight to 12 v.