You can drive a tranny with bad on no syncros as long as you learn to double clutch. That is.. when you go to shift to the non-syncro gear press in the clutch, shift to natural, release the clutch, then press the clutch and shift into gear. Just like a trucker.
I drove my old mustang like this while waiting three weeks for Ford to get the 2nd speed hub inserts (part of the syncro).
jeff