In slightly better news, I got my W running on both cylinders again.
Took the carbs off, stripped 'em down, hosed 'em down with carb cleaner, put it all back together, and she's running good again.
(Idling a little low because it's off the choke and not warmed up yet)
Also took the opportunity to try again to put the 2nd short throttle cable on (from the low bar kit) and was able to make it work (barely) this time.
Also, check the back of your headlight shell where the wires come out. There's not any grommet (at least not on mine, anyone have a grommet there?) and some of the wires are beginning to rub through their insulation against the edge of the headlight shell. I added some layers of electrical tape to stop that action. If those wires rub through, all sorts of electrical gremlins will pop up. Might be worth checking yours.