87 wireing harnes

I am droping a 383 into my 87 z28. Just pulled the 305 and dont exactly know what i should do about all the extra wires i am going to have. I am going from a electric carb to a holly 750 and guting out the smog devices. Is there a wireing harnes i can buy that would allow me to keep my power windows and door locks, or should i just cut the extras at the fire wall? Thanks