I remember watching the making-of DVD that came with MGS2 and Kojima mentioned Chinaman. You would have fought him in the chamber where you fight Vamp in the final game. Parts of the battle would have taken place underwater where Chinaman would send sharks after you. He also had a dragon tattoo on his chest that would come to life when he was underwater and it would attack Raiden.
Kinda glad Chinaman was cut, then. I *hate* the swimming section in that game. Fighting a boss while swimming sounds like the worst.