a taller spindle/tall upper balljoint "spreads" the UCA and LCA to give a different and in the case of a g.body yields a greatly improved geometry... raising both yields nothing and is no different than installing shorter springs..
a taller balljoint will improve geometry, for the lowering.. get some specific springs.. my advice is to contact SC&C (
www.scandc.com) and have a talk with marcus... he will get you steered on the right track and not feed you bull s#it, he is not a man of few words, but he is awesome to talk to and i recomend his stuff...