Hi
I have done this on my '47 1.5 ton. I had an adjustable reamer, and as 3B said above, an extension and a cone shaped adaptor that centred the extension dead centre of one end while I reamed the other end of the spindle.
From memory the clearance is .002" and I set mine to about .0015", scared if I tried to get it closer I would go over.
Kingpin size was .921"??
I set up the spindle in a vice and used a dial guage to check the clearance. I inserted the kingpin, and held it against one side, top and bottom, and zeroed the dial guage. Then I would move the whole kingpin over to the other side and hold it there tight, and the dial guage would tell me how much play there was in the spindle.
It was exacting work but it did come out perfect. I had to carefully ream each end out to just big enough, and take both ends out in stages, oneafter the other, for the measurement to be accurate. It was slow work.
I got my kingpins off Truckandcarshop. No problem overall but one of the kingpins had a .003" taper over the last half inch, this is incorrect, and it would seize in the spindle when I inserted it and did a bit of damage. I was able to lathe it correct. Watch for that although I bet its rare.
If you use an adjustable reamer, disassemble it first and clean it perfectly so theres no swarf in the channels. Work out what the change in size per turn is, and be conservative when adjusting. you only get one chance to get it right.
On the plus side, mine are perfect, and I am a beginner- so it can be done.
Good luck.
