Its probably the bellows that makes things look crooked as the folds aren't 100% square, and the funny angle of the picture. I am getting basically the same results with 2 different brand 50mm lenses on 2 different Beseler brand lens boards.
I don't know the units history from the late 60's when it was made till now, but if you can think of anything that could be changed to make a 50mm lens focus at a different distance from the film without changing the distance between the film and easel I am willing to try it.
EDIT: Sorry, everybody posted at once, I just checked it and its about 2" internally from film holder to lens board.
2nd edit: just to clarify since I'm thinking some people might have missed it, this is actually working fine as is, the only question now is whether or not the focus bellows is supposed to be almost fully compressed with a 50mm lens and 35mm film. What I read in other threads would lead me to indicate this is normal, but if someone else has a 23c II and wants to duplicate the experiment to check I would be very happy.