@DionR if you're going through all this to redesign a spindle, why not incorporate a screw in LBJ and make a divorced steering arm? Perhaps odd to have a screw in LBJ attached to the spindle, but its no different than the stock LBJ in theory.
That would extend the project and add a new level to it.
If I add the 7 degrees positive caster it will require (I assume) an adjustable UCA, but those are already designed and can just be purchased from @BergmanAutoCraft. If I redesign the LBJ, I have to design a new steering arm at the very least.
Add that it would complicate the hub bolts as right now the lower bolt is hidden behind the LBJ and has to be tightened before the LBJ can be assembled to the spindle. Adding the sleeve to screw the LBJ to would probably require dropping the LBJ 1-2" and would require the LBJ to be removed to replace the hub if required.
I guess rotating the hub bolt pattern 45 degrees would solve that, maybe.
I have started leaning towards the '73-4 LCA and steering arm, just because that arm doesn't have wear parts and the LCA accepts a screw in LBJ so it has the advantage of avoiding the low quality parts that seem to be prevalent with most replacements now.
Hmm...not sure. I will have to think on the idea some. Thanks!