Not sure what type of bit in a lathe or whatever is used by a pro, but I simply used the sharp edge of a triangular file. Had the blocks cut into splines that fit perfectly in a jiffy. Did not take long at all, even by hand.
You may not need to however, unless it is a swapped-in gearbox, or a non-Ford style pitman arm? What is it you're dealing with, parts-wise?
If you make sure to center the box first, before anything else is connected to it, most Ford boxes will have their key/master splines facing directly to the sides and front to back. An early Bronco's original manual steering gear, and some of the early power steering gearboxes, have their splines skewed by one spline (10°) so the arm is pointed slightly to the driver's side.
I've never heard any argument that says one way is better than the other, or that one way is worse than the other.
But in most cases I set them up pointing straight back along the frame, but only AFTER I determine the center point of the box.
That way once the steering wheel is attached, you can easily pinpoint the center position from there on out without looking underneath.
Paul