I've got a 74 CJ5 with a 304. Im looking to changing the ignition to a GM HEI. I know that you can buy one of these units already setup for the AMC engine, but I have a GM HEI, and was wonder what changes are made to the distributor, and if this is something I could do myself,without having to buy one. Like most Jeepers,,,, Im a tight wad and like to do-it-myself. Any information is appreciated!