She runs!! I stripped the carb again. Bought an ultrasonic cleaner, separated the jet block from the carb body, and gave everything a thorough cleaning. Oh what Joy to hear her sing!! Took it for a gentle ride around the block. The gears select nicely at those speeds. Brakes are absolutely abysmal!
Occasional backfire through the carb, but idles well. I’m a happy BSA owner.
Thanks for all the help. This forum is a phenomenal resource!