When rebuilding a gearbox assembly, it is preferable that all the wear and damaged prone parts are replaced at the same time.
Interfacing old worn gears with new can lead to meshing problems and premature wear of the new gears - the same applies for the selector forks and drum.
Order all the gaskets, seals and bearings required for reassembling the engine and transmission at the same time and combine shipping costs to just one fixed price. Try the same gasket seal used by trade professionals: 08C70K0234M. Please note, this part may have other applications in the Suzuki range.