Bill, in my opinion, GM factory wiring diagrams were horrible. They never seemed to make any sense to me. It took me many years before I could even figure out the basics! Even when I could find a set that was readable!
That being said, Larry DuBois created a set in color for the 69 several years ago and even though I have a 68, I still use his for reference since they actually make sense! I emailed Larry a few months ago to see if he was planning on creating a set for 67 and 68, but as yet, no plans. But I keep my hopes up.
Anyway, he still sells the 69 set so drop him an email at firstname.lastname@example.org
and see how much they're going for now.