www.hotrodwires.com I bought my wiring harness from him at a swap meet. Bill is a great guy, he's an older retired man that makes these harnesses for summit and jegs and they put their name on them and double the price. He can even make you a harness for a fuel injected small block if you want to mess with CPU's. Just give him a call and tell him what you are doing and he will set you up the right harness. All you need to make it simple though is a HEI style distributor and a one wire GM alternator, and just get the 12 circuit kit from him.
Any more questions let me know.