Broadly speaking motorcycle oil comes in Jaso ratings, MA & MB
There are also sub ratings of MA & MB :http://www.oilspecifications.org/art...MA_JASO_MB.php
As long as you have a dry clutch either type is fine.
If you develop oil leaks then that just an indication it's time to pull things apart and fit new gaskets anyway, most modern machines run synthetics with nothing but a silicone sealer between the major gasket faces and have no problem.
The seals are no problem, they are the same material as the new stuff.
I run all three of my bikes on full synthetics, the two four strokes with high zinc type.