RE: MVVS 120 twin boxer
TP,
This is an MVVS...
All the .15-.91 displacement cylinders (this engine has .61 cylinders) can be rotated, to have the exhaust port pointing in any of four directions...
This is best done before the engine is ever run, so new wear-patterns are established on pristine surfaces of new piston and sleeves.
However, the carburettor probably cannot be turned 90ยบ, so I cannot see how you would allow it to work properly.