96z28cali

I bought a 95 z28 parts car a week or so ago for parts I need on my car. And I wanted to help my friend out since he has manual door locks windows and mirrors. I am trying to help him out by putting the doors on his car so he can have power everything. My question is how hard will that be? Do we need to change the wiring harness or is all the wiring already there? Any help you can offer is a great help. I tried googling it but didn't find anything that could help.