Your steering column issues sound exactly like mine after I replaced my steering box with a quick ratio version. Everything is splined with a keyed spline.. the pitman arm to steering box gear, the rag joints have two different sized bolts, the steering shaft has flat spots for the set screws, and the steering wheel spline is also keyed. What I cannot recall is whether or not the base of the column spline is also keyed, but as I type this I remember I have a spare steering column in my garage, which I will we take a peek at. Anyway, I have been told time and time again that an alignment will cure the steering wheel off center problem however having had 2 alignments that hasn't panned out for me, and my steering wheel is also skewed to the right of center pretty significantly. I will check my spare column spline and get back to you but if you find a solution to this problem please let me know. I feel like a Beverly Hillbilly driving along with a cockeyed steering wheel.