Harley uses a shift dog instead of synro's and a shift cam of one gear up or down and most importantly a aftermarket builder of better than stock transmissions is Baker who was a GM transmision engineer . Prehaps if he was aware that a secondary market for american made products existed he might...
I saw the pic of your project , do you have any other pics ? I'm going to be starting a tub when I can get some dimensions and or prints to work from . dave in portland , oregon .