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.