The problem with the Lechuck sprite in The Secret of Monkey island is not only the transparent parts (which are much scarcer and available in much less variety of elements), but specially the blue outline that surrounds the character:
You can get away with that in 2D to depict a see-through character, but in 3D, I would need to do most of the character in trans-clear color, and without that blue outline, it just does not look the same and would defeat the whole purpose of the endeavor.
I did look into it, but frankly I wasn't able to make it look remotely good. MI2 LeChuck was much more appropriate for this sort of model. Besides, I far prefer the look of the character in the second game, so it was a no brainer