We used a stock harness and removed the smog wires. If you go to LS1tech in the Hybrid section there is a ton of info there. Also, Performancetrucks.net is another great site. There is an older truck section under specialty vehicles. I go by LIL SS on both sites.

1963 Chevy P/U: Forged LS1/4L80E swap and big hit of N20 coming
1973 Camaro: Low compression solid roller LS1 with PT91 turbo Built for the Silver State classic
1967 Convert Continental: Stock Cruiser