This is something that's been at the top of my wants list for many years, too. Actually I want all three characters from TGTBATU. I guess you could say I started a "project", but because of so much else going on, I haven't gotten much farther than doing some sketches of their costumes and gear, and gathering a few odds and ends.
The head sculpts was obviously a big obstacle, but then I heard that H2 already made Tuco and Angel Eyes! Their Eastwood head looks like it would do very nicely for Blondie, or any of Clint's "man with no name" characters, for that matter, even Josey Wales.
So the sculpts are there, you'd basically just need their costumes, gear and weapons. Tuco wouldn't even need a gunbelt. By the end of the movie he carried his pistola on a cord around his neck and just stuck it in his pants pocket, the spaz!
Anyway, maybe the best approach would be to see how many other Freaks are interested. If you got enough people on board, it could be a collaborative effort, and maybe then someone could be commissioned to make the costumes and other stuff. What do you think?