Do a Google search. There are several links for you. Too much to type when it's already been written several times. It's nothing personal.
Just looking for info or a link or even a simple helpful answer from some one thats done it. I'm thinking I might have put a 12v coil and ballast resister and leave the rest alone. I guess the positive negative ground is not an issue. Its going in a hotrod so why not go to 12v. I have a rebuilt generator 12v. Ill take reliable and ease to get parts over original.