It sat for 2-1/2 years problem.
It needs new float needles.
When they sit the rubber tips get out of round and gummed up.
You cannot just clean them with steel wool and put them back in.
Thats why the floats are not shutting off.
It needs to have the idle jets removed and cleaned until you can see through them.
Also replace the fuel filter, and drain the gas tank. It collects moisture.
Syncing carbs is the VERY LAST THING in tuning up the bike.
carbs are last and syncing is very last.