I have done lots of research and read that some of the animation was done for part 2 but is lost or destroyed.
Bakshi has been selling off all of his production stuff on ebay so any or all pre production artwork in his collection as well as production cels, are being sold off and it's really a shame because they would've been great to be printed up in a book or used on a future dvd release.
Saul Zaentz has blocked the publication of the script by mr. beagle and denies owing him any money based on a verbal agreement over the script, on his site mr. beagle makes a pretty good case for being owed some money because of his inspiration over the jackson films.
now that he has sold all of that stuff and continues to there never will be a restoration or compilation of what 2 would have been like using any completed animation or storyboards as well as the script, sort of like ocpmovie's thief recobbled.
everybody seems to hate Bakshi's Lotr, yet Peter S. Beagles script is far more close to what tolkien wrote than what peter jackson, fran walsh and phillippa boyens wrote. If a yound teenager named peter jackson had never seen bakshi's version the trilogy would never had happened.