2 suzuki sv 650 oil drain plugs, at about 2 bucks a piece. Comes with crush washers

has small heads to fit beside the spark plugs... Then, find small rubber hose the same size (ID) as the carb balance tubes, cut it into two pieces. One goes across the carbs, one across the manifolds as balance tubes.
Finally, get a rubber stopper, or wine cork to plug the hole in the airbox.