So, it definitely isn't the starter, but thats all I know.
This past weekend, I finally got the truck towed home, threw a fresh battery in it, tried the ignition and this is what happened. I was floored. Didn't expect it at all.
But, the truck still doesn't run just yet, so I got down to business troubleshooting. First on the list was to change the oil and oil filter. Check. Next came spark plugs and spark plug wires. Check. New gas into the tank, and the fuel tank selector switch set to the proper side. Check. Fuel gauge shows fuel in the tank. Check. All good news so far. In testing the electrical components and accessories on Saturday (wipers, lights and radio are all working) the circuit for the hazards got left on, and the battery was drained when I came back.
A quick charge later, and the battery was full and ready for another ignition attempt. Somewhere along the way, I also swapped out the ignition switch for a newer one, and stuffed it back into the dashboard.
On that next ignition attempt, the starter motor wouldn't crank over.
Unfortunately, thats where I'm at until next weekend. The plan is to backtrack, and swap back to the old switch, and leave it out of the dash until I can confirm it'll get the starter to crank.
Then I get to move onto troubleshooting the fuel system. Seems like gas isn't making it up to the carburetor. No leaking fuel lines means the diaphragm in the mechanical fuel pump is probably old and dried out and overdue for replacement or rebuilding.
Before I do that though, I'm going to replace the section of fuel line between it and the carb, and install a clear fuel filter so I can see if the pump moves fuel up the line to the carb. An extra set of eyes would help!