Ok this is easy- I tried the rotor phasing test, drilled the hole then swapped out the good cap for the 'test' cap, connected the timing light to #1 wire and hit the rotor with the light while revving the engine.

THe rotor didn't budge Stayed rock steady during the whole process. I'm guessing this means there's something wrong with my vacuum advance? It's connected to the left vacuum port on my Edelbrock (1405), and I think that's the ported vacuum.