Unsymmetrical steering issue

I rebuilt the front end of my '63 Dart a couple years ago, and ever since, the steering wheel gets only 1.5 rotations to the left, but 2 full rotations to the right. My turning radius to the left is annoyingly compromised by this. (It'd be okay if it was the right side being compromised—after all, how often do you do a U-turn to the right??)

Last week I replaced my run-of-the-mill parts store rebuilt power steering gear with a nice, tight, quality-rebuilt Redhead gear, and put in a new pitman arm as well. I had been hoping that in the process of replacing these (they needed to be replaced anyway), this problem would be fixed, but it's still there. Before attaching the pitman arm, I attached the steering wheel and it did have equal turns to either side from center at that point. After attaching the pitman arm though, the problem was there again. I'm pretty sure it's impossible to incorrectly attach the pitman arm to the steering gear output because they're keyed together and the output shaft only does about half a rotation total, if I'm not mistaken.

If anyone has any ideas of what might be causing this, I would love to know, and would really appreciate it!
Dave