The dist. cap I removed was the red-orange-brown Bosch type. I replaced it with a BorgWarner, which does fit now that I've gotten all the parts lined up right, and I also bought a BorgWarner rotor. They are, unfortunately, grayish in color but I'm likely to own this car long enough to know which type of ignition I have.

Since replacing the coil and wrapping the bare wire, we've not had further symptoms so I am increasingly optimistic that we found, and corrected the problem.