There is no need to put Qui-Gon at the end of Jedi. Luke wouldn't know who the hell he was. Just having the 3 force ghosts that were part of Luke's life is perfect as it is(pre 2004). Adding Qui-Gon, IMHO, is as bad as adding Hayden to the end of ROTJ (one thing that is definite to return to its pre 2004 state in my edit)