You may find some useful information in the following tutorial I did about a year ago
https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/1164695/Re:_How_to_fit_new_kingpins_an.html
Grigg
Really nice job Grigg. I would have tried this had I known but did mine some time ago. The stock replacement bushings fell thru the spindles. Not sure how much clearance this indicated but probably less than the .020 you indicated the filler would handle.
