I checked continuity on the key switch at the very beginning of this endeavor; I did it because the terminals weren't clearly marked and I was curious about the two "On" positions; one to the left and one to the right. As it turned out, either left or right "On" connected both output terminals. So one terminal goes to battery and the other two terminals light up whatever you want no matter if you turn the key right or left. This is a generic NAPA key switch. I found it strange that it worked that way: two possible On positions and both were All On, but that sounds like a common oddity with old AD key switches.
The replacement key switch I bought from Classic Parts is a reproduction (the one with the lightbulb) and it also has two "All On" positions. I wasn't able to install that switch since it didn't come with a bezel (and the NAPA bezel won't work). Most likely it was me messing with the old, crusty wires that failed the Ignition wire, but for the life of me I can't see where.
I did make those other tests, + at the coil was not hot no matter the key position, and my suspected ignition wire was not showing continuity with the coil. I put the jumper to the coil on the key switch so it's easy on/off and ran the wire through the firewall. That should tide things over for now, and I'm going to start shopping for a new wire harness.
