Denny,
Not for these old trucks, but plastic king pin bushings are common. I'm not a fan of them but that's what's in my front axle (mid 90's GM) because that is all that I could find at time of rebuild.
So, my thinking is if plastic bushings themselves don't get pounded out, and that's the wearing surface as well. Then using something like Loctite 660 which is designed to fill a gap and support a bearing/bushing is OK. All it needs to do is fill the space and stay in place, the load and wear is in the pin and bushing, all the plastic needs to do is not squish. So the filler needs to be good in compression, which I expect it is, that's it's job.
I understand your hesitation but personally feel the 660 and similar filler/bearing retainers is a good fix for moderately worn spindle bores as well as a good way to prevent wearing out spindles even if the bushings fit as new, better to lock them in place.
Best I can figure the full floating king pin bushing was simply a quick cheap way to assemble axles on an assembly line. I see absolutely no advantages in life and function. To do it right (as nearly all other king pins and bushings are) they should have pressed bushings in and reamed them to fit the king pins.
Grigg
