Help with no power??

Mattax, my factory '70 manual is the same as the one you show in your post#9. I believe it's the most accurate, but, I don't have a '70 E-body harness in front of me. The first diagram you show in post#15 I believe is from a Motors manual or similar. I tend to believe the factory manual over the aftermarket ones. If so, the power off the starter relay would start out with the 16 gauge dark blue fuseable link, go through the round white connector, become a 10 gauge red wire, and plug into socket 16, which, looking at the firewall from the engine side, would be the center bank top left socket. That's at least the place I would start. After 50 years, anything could have happened to change that.