Broke

Turns out it was just the pedal assembly. The hook that the clutch cable latches on to had some corrosion, and after 42 years, it finally broke off. I had the car towed to NethKen Associations, and as usual, Ken did a nice job.  I also had him fiddle with the choke and lower the idle.  Car runs great now, though it doesn't seem like the choke is working properly when the car is cold.

Here's what I saw when I was on the side of the road waiting for AAA.  Looks broken to me, but I'm no expert.

No resistance in the wobbly, broken clutch pedal (left)