wiring harness from monte carlo?

[thaubol]

I currently have the 305 out of a monte carlo sitting on an engine stand, being cleaned and readied to be put into my truck. Because I will also be using the auto window switches, ac, cruise control, and a few other things, i was considering using the wiring harness out of the car as well.
i will be installing a t5 behind the engine, and i was wondering if anyone knew how this would effect the ecm, or if there are any other major changes that im going to have to make. I realize this may not be super easy, and many people will say not worth it, but im a kid working through college and i have a lot more time/brain power than money at the moment...
if anyone has any knowledge, experience, or advice for this it would be a great help to me.