The engine has been buttoned-up and mounted back in the bike. I checked that everything is re-wired properly, and the electric starter works! The carb mounting needs a bit of tweeking before I can try to start it up, and I have not installed the torque converter.
I removed the dipstick from the extremely long upper oil filler cap and shortened the tube so that it is usable with the tank in place, not to mention a lot less awkward looking. I initially tired to weld the two parts together with my hot-air plastic welder, but none of the plastic welding rods I have would adhere properly. In the end, I simply used two-part epoxy and covered it with some plastic-friendly black spray paint.