I used the stock 2002 camero harness and mated it together with my harness and a 1997 Z28 fuse and relay block. It was pretty easy just had to use a good diagram and know what all the wires are. I used all factory plugs and mated them with the different harnesses. I used Alldata to decode all the wireing. I used a 3 wire senser for the temp guage and the oil pressure sender that comes on the LS1 workes great with a factory GM guage. It tool alot of soldering and heat shrink so you should know alot about cars and electronics before you attempt to make your own custom harness. I'm not trying to discourage you or say it is impossable but you have to do a good bit of research before you start. Anyway several others have made their own including Farmtruc. I could help with specific questions if you have any.