Here is a fairly good and interesting article about front end geometry:
https://www.glenngoodspeed.com/volvo/caster.htm If you stand at the side of your truck (driver's side) and study your front axle without the wheel mounted, the axle should lean backwards. This is to say your pivot points (top and bottom of the steering knuckle) must lean backward. It won't be a lot, but you can see and measure the angle. How much that angle should be depends on several factors. As mentioned above, the condition of your kingpins, bushings, wheel bearings, etc is important. Tie rod ends and your drag link connections are also important. I would think you probably already checked these but if not, please do.
Once you have a good understanding of geometry, you can set up a front end that will run straight and true with very little bump steer, wandering, etc and one which steers pretty easily. One item these trucks needed was an anti-sway bar.
Yes, 6 degrees might be too much, but at this point there are too many variables to say. That's why I told you how a friend and I solved his problem. We had no idea what degree of camber we needed, but once we found an angle that kept it going straight and didn't require Bluto in there trying to steer it, we were good to go.
Good luck,
Jon
