Went through a similar situation on my 49 3100 last summer. The spindles were worn and the new stock sized bushings were too loose. The axle was fine.
Not having the tools or means to DIY, I found a local machine shop that reamed out the spindles true then custom made the oversize bushings to fit a std sized new kingpin. Wasn't cheap, around $125 per side, but they fit and work great.
Good luck
Dave
