Happily reporting back. Replaced orings on the main jets, float bowls, and bowl screws. Took out a couple of the emulsifiers and they were very clean, so I left the rest. Cleaned bottom of bowls and inside the carb where it had the white crud. Replaces missing leaf spring.
On the pilot jet that wouldn't stay in, I opted to use some JB weld Steel Stik. After activating a chunk of the expoxy putty, I made a very small snake and wrapped it around the threads of the jet and pushed it into the threads, then squished it into the jet hole. After waiting for it to set (5 min) I backed it out, cleaned around the hole a bit, and left the jet out for another half hour for it to cure. Then sure enough, I was able to screw it in and it showed no signs of wanting to fall back out, although I didn't try pulling on it too hard.
After a couple of minutes of trying to get some gas in the carbs, it fired up! Rode it around the block a little when it died. But it didn't take much to get it back going. After a while, it really perked up. It runs absolutely beautifully! Even much better than when I first bought it.
My next goals are rebuilding the front brake, finding a brighter headlight, cleaning electrical contacts, and heat shrinking some wires that keep coming loose.