SUCCESS! (Sort of)
Finally got the B running today - turns out that the carb vents were not completely clear. I had tubing on them, just in case of fuel spurts/backfiring issues, and the tubing was partially blocked - apparently just enough to interfere.
It's running, but won't do so without choke being engaged. I've played around with the mixture screws, and got it closer, but still won't idle. Interesting that there are several recommended initial settings of the mixture screw to set the level of the jet. But then, whoever claimed this was exact science? At least I'm on the way. (Still say the TR3 was easier!)
Mickey