I agree, you are referring to the one in the Lucasfilm archives book right? It's odd that Raiders had more of a science fiction feel in those early concepts. The only part of it , I believe, that made it into the movie was the "Flying Wing" which never was a real plane.
Yep, that's the one. I think Lucas was going for an exaggerated Bond villain feel for Dietrich with the mechanical arm...since Spielberg wanted to do a Bond movie so bad back then.