The first concern would be whether or not the worn spindle bores are round, or egg-shaped. If you're going to fabricate an oversized bushing and ream or hone it to fit the kingpin, the hole the custom bushing goes into must be round. A good machinist could probably bore the spindle holes oversize, and in line, and then fabricate bushings to fit the holes properly. I do something similar with 216 connecting rods when I'm fitting Perkins diesel insert bearings to them.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
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