With fixed lowers, why get adjustable uppers, unless it is a future modification plan.
If it drives okay as in no vibrations, no death wobble, then the caster is within tolerance for the stock length arms and your lift. If that is so, adjust them to the length of the stock uppers, 15 inches as I recall. just pull one and measure center of eye to center of eye, dial in the new one and install. If you want to correct the pinion angle a little bit as you install the new ones go ahead and dial them out 1/4 inch or so to bring the pinion and caster back up. That will be raising the pinion (Lowering the ujoint operating angle) and bringing the caster more negative.
Oh, it is a good idea to do one at a time to lessen the wrap of the front axle.