Let's put it this way- the axle doesn't know right from left, if you do happen to spin the axle and get the right side on the left it will not matter. The hole in the axle for the cotter is a through hole, it has no taper. As has been said here already if there should be some deformation to the edge of the hole from the lock washer and steering stop you may need to run a drill or even a rat tail file and dress the hole a slight bit. The only taper is not in the hole, it is on the cotter, the cotter is the same diameter it's whole length, with a 3* taper wedge machined on it to lock the k/p as the steering stop nut is tightened.
Made the way the cotter is means the machining tolerances can be a bit "looser". Think about it, if the cotter was tapered to fit the hole then the taper that holds the king pin would have to be spot on to do it's job.
