Booooooooo
Got the new timing springs installed and set the valve lash. Got it running a little better but was still backfiring. Went around the block a few times, trying to enjoy myself but disappointed in the lack of performance, and went back to the garage. And it was then that it hit me. By sheer coincidence, I looked down and noticed that the left pipe had a some carbon around the muffler tip, and the right pipe had a wet oily/gassy collection at the tip. I reached down, and sure shit, the right muffler is ice cold. I pulled the plug and it was soaked with no carbon what so ever. It doesn't take a rocket scientist to see that there is little, to absolutely no firing out of the right cylinder.
It's obvious the armature windings are shot and not providing enough electricity for a consistent spark. This clearly explains the backfiring and complete lack of power.
Good news is that damn near everything except the motor, trans and the magneto itself are now brand new.
Bad news is now I'm going to have to fork out another few hundred bucks to actually get this thing running like it should.
Oh the joys of trial and error when restoring a 55 year old bike that you previously knew NOTHING about. Thanks again everyone for your knowledge and advice.