I have a 95 Corvette Lt1 in my 48 Chevy truck. I purchased an aftermarket harness from Howell Engine Development who also re-flashed my computer to remove the emission and VATS "stuff". Not cheap but takes the guess work out of it. Your options are to rework a factory harness (if you have the time and expertise) or purchase a stand alone harness. There are pros and cons to each approach. You would still need to figure out someone to re-flash your computer no mater what route you choose.
I suggest looking at the follow forums and asking questions there (that is what I did)
http://www.camaroz28.com/forums/lt1-...engine-tech-9/
or
http://shbox.com/1/4th_gen_tech1.html
I found both sites full of information that was very helpful. Because your application might be custom for your application there is not a answer that will cover all of your questions.
Marc