SOLVED! I got the truck running again. Turns out it was very simple, and a few of you mentioned checking the rotor. Klhansen was the first, but there's an old post that I read years ago that says something like, "if your distributor cap is too tall, it won't contact the rotor". Well, my distributor cap isn't too tall, and in fact the engine was running at the time of the problem.
Turns out the problem was that the top of the rotor wasn't contacting the distributor cap. I bent upward the center contact on the rotor, and I got fire. Hotrod Lincoln's' suggestion of attaching a spark-plug wire directly to the terminal would've lead down this path.
The truck was very hard to start, possibly because in the course of this, I replaced the points and condenser, and maybe the points need fine tuning. But I was able to drive it back home (about 10 minutes, which is quite an excursion for this truck).
By the way, did you know a points and condenser and feeler gauge (now I have 3 of those), cost $50 these days? I was flabbergasted.
Thanks for all the suggestions!
