At first look, the vacuum leak/lean condition surely looks like a problem, and hopefully you tried blocking off the advance hose to make sure.....But if the WD test showed nothing, and the fact that you've tried several carbs, leads me to the ignition as you have speculated.
This is a complete shot in the dark, but how do the plugs look? If you're running a electronic box, has the ground become compromised/corroded? Is your battery/charging system putting out 12+ volts? And then there's the coil? I'd probably look to try another one if you can't find another issue.
Like I said, these are guesses, and just a attempt to get you thinking about other things. After all, it could still be a vacuum problem that's just eluding you?
