I don’t think the harnesses are bad at all. Never had any issues. TPS, knock sensor, IAC, CTS, temp sender, MAF, CPS, alternator, O2 sensor, injector wires + grounds, other various grounds and I think that’s it. Biggest PITA in my experience was on a 240, had to remove the AC bracket and pull the alternator harness through. Well, not remove, but pull aside. 4 bracket bolts removed, zip tie the AC+PS to the fender well (again, 240 not 740), and the harness was easily pulled through.
Trust me there are much, much worse cars to work on. You’re probably used to working on LS based cars that only have a handful of wires and the entire harness easily disconnects under the bay.