King pins are a harden steel, careful using one as a drive, shards can and will splinter off and go flying.
It's best to use a full length reamer, but if you take your time can probably hone them to size one at a time and still get a decent out come. One of mine ( 1/2 ton ) about fell out, the other took a lot of heat and a big hammer. Going back together, was easy after a good cleaning. Mine just needed a touch up with some 600 grit paper rolled around a wooden dowel in a drill motor. They are still tight 15 years later.
