There is always an awkward moment in the opera as Faust changes from old age to youth. Since he is a plastic surgeon, I see his “old” face as a falsely ageless one– we have developed our own Mephistophelean fountain of youth. To transform him in the spirit of this opera, I would bring on Hollywood Stylists who change his appearance in shadow. This keeps the action continuous in a way that serves the story. Mephisto, of course, has better powers and Faust is truly transformed.
Mephistopheles takes Faust to a club, where they will party like rock stars!