I have only done king pins on 47-55 1/2 ton trucks (which do require reaming of the bushings). When I could not remove the king-pin, even using a small hydraulic press, I have taken the axle assembly (with spindles/knuckles attached) to a front-end shop.
If you do not have the reamer tool (for the bushings), you might want to find a front-end shop that has someone who will work on your assembly. If a king pin is loose in the axle, you will need over-sized pins and the holes in the axle will also have to be reamed.
A few years ago, I needed an axle reamed for an over-sized pin and was quoted $400 (lowest quote) just for the reaming. I bought an adjustable reamer (about $30) on eBay and did it myself (1/2 ton truck).
As posted above, from ashton onwards, you need the right tools (and experience does help). Check around for a quote from a shop - tell them you will bring them a cleaned assembly - the axle with knuckles in place.
You might also want to check around to see if you can find king pin sets for your truck - standard size, 0.10" oversize pin/bushings, and even 0.020" over-sized pins and bushings. Don't buy them, just find a source This would assist the shop in the time needed to find old parts.
What is the diameter and length of the standard king-pin for your year/size truck?
