I almost bought a thermal camera just for that purpose .... something I've wanted a long time but can't find enough reasons to buy
I'm using a new AC harness, and new Engine harness, quality seems as good as OEM, but that's not saying a lot.
Was just noticing last night how cheesy the 30 amp fuse setup is. At this point I've thoroughly cleaned any original terminals, applied some anti-oxidizing grease, checked the resistance as much as possible, going to have to keep my eyes and nose ready for signs of trouble. Obviously these system were sorely under-engineered, even most low miles cars show signs these connections were burning up long before they became "vintage".