The float sometimes sticks so I usually shot off the gas flow when stopped.
This might suggest that the carb and/or fuel filters are a bit gummed up from storage, I would take the carb off and give it a good clean, especially the pilot jet which needs a #78 drill or guitar wire to clean out properly. You might need to take the petrol taps off and check the gauze filters are clear.
Then I would also check the battery
voltage as Boyers don't work too well at less than around 12v, maybe running the engine is causing a current drain.
The missing Tufnol washer in the inlet manifold won't be helping matters, so I would get that changes asap.
As the bike has been standing, I would also change the plugs and check the HT lines are OK, also check the coils have the correct primary and secondary resistances.