I have a 29 chev, and when looking at my front end and king pins, I found it hard to turn, but very easy once jacked up. However, I did have some up and down movement. I decided to redo king pins, engineer to fit in the spindles with new king pins. Once I put together, no up and down movement, easy to turn with wheels jacked up, BUT still hard to turn on the ground. The pins do have a bearing on the bottom that was being shredded, and the new pins come with these bearings. SO, if there is a bottom bearing, and it worn, it did NOT effect the end result- the stearing was/ is still stiff on the ground, and my machine is the chev tourer, a lot lesser weight than yours. Hope this helps.
If I knew the bottom bearing was being chewed up, I would have replaced it, but it did not appear to make any difference, and car travells very well on roads, even at 60 mph.