I'm going to be honest and say that these sound like bad ideas. Actors change between movies all the time. Yes it's a little jarring, but resorting to hackneyed plots involving plastic surgery doesn't do anything but put salt on the proverbial wound.
I do think you did a good job integrating the clips from those different movies in the Norton-Ruffalo scene. What movies did you use? I only recognized "The 25th Hour" and Ang Lee's "Hulk".