fair enough. So just to make sure I'm understanding your suggestion, are you saying to lay out the factory harness, buy the needed connectors,ends, plugs etc and get the same color wires and custom make a harness using the original as a pattern?
Pretty much. Assuming replicas are not available or out of price range.
Label connectors and remove factory harnesses (plural) one by one.
Layout factory harness & remove tape,
Make a list of wire color, size and lengths needed to buy.
Buy new terminals,
Only Buy new connectors if needed.
One harness at a time, replace every bad wire and/or terminal connection.
The only connection that can't be done at home like the factory is the welded splice in the main under dash harness.
Here's where Kieth's suggestion of having a good used harness might be easier for a guy in your position. There's other ways to do it - but however its done, that's a very important junction.