Are you doing this because your alternator died?
A internal regulated alternator isn't going to turn your truck into a street rod. It's just going to turn it into a truck with a cut up wiring harness.
My suggestion. Summit sells a rebuild kid for your old alternator made by
QuickStart that will increase your external reg alt to 105 Amps. But first, do a little reading on this subject.
Autoshop 101 Go to the technical Articles and start reading. I haven't found anything better than this on the web. Don't let the fact that they use Toyota circuits and systems as examples, turn you away. They are for the most part very similar.
Internal Regulator Has a pictorial wiring diagram. Click "previous" at the bottom of page for more info and diagram with amp gauge.
67-72 wiring I don't know how close this is to a '66, but it may help.