smooth move

is there a formula(lift to length) for extending the front control arms? i'm at the limit for stock arms and i want to lift my xj about 2 more inches. it's e
asy enough to cut and reweld a pc into the arms or completely replace em, but i don't know how much to lengthen them. thanks.
i guess i could cut the old ones out and make the lift, then center the tires in the wheel well, then measure the length needed? does this sound like it would work? i'd much rather have a formula to back up my measurements.

98cherokee531

General idea. It didn't work for me though but it's a start. Second pic is caster settings. I run about 5.5* of castor.

smooth move

ok thanks. i'll do it the way i described and compare that to the table you posted and see if it's much of a difference.