AC Wiring harness vs. Non-AC Wiring harness

Which honestly, is probably cheap insurance in the long run. I have enjoyed doing the work thus far. But I things tend to be far less fun when you do them the second time around....
You can buy a new under hood engine harness as well which is cheap insurance. A new dash harness is harder to swallow at $500 and not as obvious if you are going to need to cut it up for the new cluster.