I just got my ball joint spacers in for the lower a-arms on my 2wd.
Don't have any numbers on improvements (lift), but I think it helped a bit.
The 2wd setup is different than the 4wd because the torsion bars are adjusting the lower arms on the 2wd, and the uppers (right?) on the 4wd.
My Fabtech kit came with an upper spacer that supposedly lifts the front an additional 1/2" (It is a 1" spacer).
Unfortunatly, I was limited (for now <img src="/forums/images/graemlins/evil.gif" alt="" />) to a 1/2" spacer for the bottom, and with a very rough measurement, I think it helped a bit.
I did loosen the torsion bars a little too though, so that also lowered it back down again (and softened the ride a bit too).
Just watch the ball joint and spindle plate clearances and you should be fine.
Take a ball joint off (or get a replacement) and use it as a template and cut out a spacer. Just leave enough room for the up/down motion so things don't rub.
Good luck!
Todd