Wiring Harness Interchangability 84 Truck, 72 Engine

[thefraze_1020]

A while back, I posed the question "how hard is it to put a 350 out of a 72 into an 84 that originally had a 305, mated to a Muncie 4-speed?"

I now have a new question. When I pulled the 305 a couple weeks ago, I noticed that the wiring harness wasn't in that great of shape. If I remember correctly, the engine wiring harness out of the 72 was in better shape. How easily can I swap the engine half of the wiring harness? In other words, how much different are the harnesses from a 72 and an 84?

Also, my radio/ speaker wiring was modified a bit in the cab. At this point, should I just be thinking about replacing the whole harness?