http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm0903.htm

As far as I can tell, the splined sector shaft is not tapered (picture).
The pitman arm lock washer and nut, when tightened, should obviously have thread underneath all of the nut.
I've seen the nut and shaft end being flush. I've also seen the nut in a little bit.

I make sure the splines are clean and not damaged before I put the pitman arm back on.

"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."