Oh, I checked the waveforms at both ends of the coil windings and just dialed it in until they matched.
Anyhoo, thanks for the info. After making this topic I connected the scope to the other set I was having trouble with; turns out the very weird waveform I was getting before was due to a bad probe ground. Finally I hooked onto the yoke clamp and was able to dial in the proper waveform. However, it isn't quite equal to the waveform I get at the other terminal which lacks the horizontal harmonic "bump" of the former. I probably have to fine-tune the Heathkit's coil (or not, I have to wind a new one anyway so why bother).
Here's the waveform at the other set along with an excerpt from the manual. It's as close as I could get.