I did the same swap on my 91.... I ditched the computer for the original I6.. I then disconnected the original harness, layed it out on a table and eliminated everything that wasn't needed anymore.. Be carefull though as not to cut any main power feed to the inside fusebox, fuel pump, gauges(if your keeping them), etc.... The stock harness can feed you SBC distributer, alternator, etc without any issues... It's actually a very easy swap if your really comfortable around electrical work, not many are... Good luck with the swap.. PM me if i can help out in anyway..