Irwin,
Needle or roller bearings do not like partial rotation applications, plain bearings IE king pins and bushings are the BEST way to pivot a spindle in a beam axle. You could do as you say and put the bearings in but, you WILL see more wear in the pin and spindle. The roller are hard steel and your pins and spindle are softer material. The roller will wear this stuff out in no time. Also the surface area of the bushing is many times the contact patch of roller bearings. If you grease the king pins they will last a long time and the steering effort will be very low.
So in a word DON"T!
