I mean, Soon as Solo opens his mouth to the Officer in the Detention block, he's gonna realise that something is up...Well realise sooner than he already does that is...... "
Oh, don't worry about THAT... I'm sure GL can seamlessly edit that scene out to tie in with his new vision. Or he could just redub Luke and Han's voices with Jango's throughout the entire trilogy so then he could say, "Well, actually, Luke and Han sounded just like Jango all along..."
Another point: He would also have to redub Boba Fett's voice in ESB to sound like Jango as well...