For sure ream the bushings to the proper size for your kingpin, but on an old style steering box on an early Jeep I was chasing steering slop and decided to adjust the backlash on the steering gear, using the locked adjustment screw on top. It was sweet, took all of the play out of the wheel, but then I turned it away from center and it locked in place. The worm had worn a bit in the center portion, but not on the extremes so when I adjusted out all the slop in the middle it was an interference fit on both ends. If you played with the gearbox adjustment you may want to revisit that with the box disconnected like Jim mentioned above.