That's fun! I do think he could have been more attentive to a few geometric details like the face angle and the distance, and maybe if he'd bracketed the aperture a bit he might have ended up slightly stopped down from where he was. Starting with a shirt more like George was wearing would have been a good way to get the chin to be in the same place as the other portraits. Everyone in the other portraits has an open neck, so that (to me) is part of "the look" that he was going for.
I don't have a wide array of modifiers at my disposal, but if I did this would sure be a fun project!