Truck Fire!!!

[Chevy 350 Fan]

Hi guys Im a Junior in High school. My first car/truck was a 72 GMC C20. 350 motor TH350 trans. I painted it Orange and white. I did some engine work and interior. I put glass packs and headers on it. It sounded great. The trans blew up after owning it for less than a year. No I wasn't racing it or beating on it, I always baby it. I think it was the original trans never rebuilt. I dropped the trans with a buddy and I took it to AAMCO to be rebuilt. It ran good for the rest of the summer then I parked it for winter and put a cover over it. Here comes spring and all seems good I put around 30 miles of city driving on it. Spring break comes and goes. Then the first day back. Im driving it to school I had gone less than 2 miles and I feel no power I look at my tach it reads 0! I let off on the gas and it came back to life momentarily I pulled over only to have tons of smoke starts billowing out from under the hood. I open the hood only to find the engine compartment is on fire. I started freaking out. I called 911 then my dad and they showed up about the same time, even though the fire department is right across the street. Fire fighters decide to piss me off by opening the hood with a pry bar even though the latch is right there. I got pissed and yelled at him then he called over a cop who was directing traffic. As the cop is walking over another firefighter comes walking over with an axe. I went ballistic and told him there was no way in hell he was using that on MY truck. He was a prick and said "I don't give a ****" I told him to F himself. He didnt use the axe thank god. I talked to neighbor of mine also just in high school. he said he saw flamed under the truck a good 3/4 mile back before the truck died. IDK why he didn't say anything or do anything. But, anyway enough of that. Im looking into parts and Im not sure what kind of wiring harness to get. Ive ordered parts from "classic truck parts of America they specialize in old GM trucks. I've been very satisfied. Ive seen a classic wiring update kit for like $500 ouch and a universal harness for half the price. suggestions would be much appreciated thanks a lot guys!