I actually have some sheet music for La Cumparsita, which I got from a Latin-American songbook at the Portland, OR public library. A bunch of fake books have it also. If you like, I will try to send it to you [if I can find my sheet music stash], but it really is pretty easy to find if you have access to a medium-sized city library."La Cumparsita," BTW, means "the masked one," I think.
Genie