First off welcome to the site. Does your truck have a story ? Maybe you can visit the "welcome" section under the "general site info" section and introduce yourself.
The wiring harness that is sold by CaptKoas on this site is one of the most complete wiring harness out there. It has 12 different features that can be wired in, and it is year and model specific, not 73 - 80 or so.
I plan on buying the same when it is time for me to do mine, and everything that I have read about this wiring harness, you can pick and choose what you want to include or not. Like in 77 when they had some models that had pw and some did not, you can tell them if you want pw or not, so you don't get a wiring harness that has extra plugs that go nowhere.
If you do get it and install it, do a write up on it and post it. As far as I know no one has done that yet. It would be nice to see one installed with pics.