my trans. opinion= .02 cents, maybe less
I think if what you really want to do is tinker and you like the challenge of this sort of project, then go ahead-- it would certainly be nice to know what other trans. might work. However, I think you are basically pole-vaulting over piss-ants! Unless you're drag racing, or have a serious mechanical jinx, the Alfa trans. w/ the right lube will shift fine and will likely be the least and possibly last of your problems.