I'm asking for opinions

Buy the truck back and fix it, would be my vote. I really like that dually 12 valve as second option. Cummins all the way !!!

x2

junkyard harness is probably ok- just be smart and buy one that looks fresh and is not hacked up. You can also find on craiglist/ebay when people part out vehicles, usually they are parting because they blew a head gasket- not because of electrical issues.