According to the 71 wiring diagram, there is a black and yellow wire that runs from the ignition to the starter solenoid. This wire's terminal should be cleaned at the solenoid too.

Finally got a parts package in from PO and figured it out. I had a faulty ignition switch. Thanks for the diagrams, pics, and links though, I plan on cleaning up a lot of the wiring on it in the coming months. I have seen an uncomfortable amount of splicing while hunting the problem.

Thanks again guys!