Runs rough when it runs

I have an 83 camaro and recently dropped in the entire drivetrain from a wrecked 88 IROC Z28 (according to engine code). Started the other day and the negative cable off the battery split. I replaced the cable and now the car won't hardly run. I've checked all the ground cables and they're good and so are the fuses, or at least those that I could find. The car runs extremely rough, once it warms up it will idle but as soon as you put it in gear or just give it some gas, it almost dies. The timing is correct, I've replaced the distributor, plugs and wires. Any ideas what would be causing this problem?

Cheers, Noegrups

check the positive cable too for corrosion

New battery and new cables, no corrosion.

If it ran fine before the cable problem and now it doesn't I hope you didn't fry anything like the prom...etc....