Also, the Metropolis parallels don't stop with the SW rough draft. Consider that Joh Fredersen is the villainous father of the principal hero, Freder, and that Fredersen the elder ends up being redeemed at the end of the film. I think that Fritz Lang's film was very much on Lucas's mind when he finally decided that Darth Vader was Luke's father.
Which also makes me wonder--could we make another link, between the evil mad scientist Rotwang (who always dresses in black, and whose house is decorated with occult pentagrams) and the sorcerous Emperor of ROTJ?
Of course, the Force lightning that Palpatine shocks Luke with in ROTJ is another idea derived from the 1974 rough draft, namely from the electric torture General Darth Vader uses on Leia Aquilae. (Poor Leia. Between this, losing both her parents, and the heavily implied offscreen gang-rape, she's clearly the victim of a conga-line of trauma.)