Carbs are synced as of today! Honestly the bike is running great now. Starts on first crank. Idles very steady right at 1200 rpm. No more pops or backfire. Pulls strong all the way through the rpms. doesn't bog down or sputter. slight lag to return to idle when revving in neutral, but when riding, it doesn't feel noticeable. Maybe running a tiny bit lean as I returned it down to a more modest jetting, but im gonna give it some time so I can get a better feel for it before playing some more with jets now that im confident its ridable and not gonna die down the street every few minutes.
I'm super happy with the progress so far, being this is my first attempt at an older bike like this!
But now im just curious, Why can the bike run fine with the right spark plug disconnected (while trying to do the dead cylinder method after balancing carbs), but die immediately when the left is disconnected? Why can the right side not continue to run?
(it did have the lower of the two pressures when balancing them today, but they are now spot on even)