I've found another model here, in OBJ format:
http://www.royloo.com/free.php - the link is just under the image that's in the 4
th column along and the 12
th row down.
It's lower-poly (12,198 faces; the HW2 one has 26,000) and has some textures that look somewhat low-resolution to me.









(There's also a mostly white texture labelled "Yamato_alpha" that I've omitted).
Not sure about how to get the textures to appear on the model. I think I have to somehow edit the OBJ file so that it references them.
Who do I have a feeling that would hit the cap of maximum rotating subsystems (50, aka 25 multiparts)?
Hmm. Didn't know about that.