I made a chart showing approximately how far upper and lower ball joints would have to be moved (upper-back/lower-forward) for 5 and 10 degrees of added caster, while maintaining spindle pin location. I included measurements for 1/2" taller lower ball joint and for 1/2" and 1" taller upper ball joints. I am sure there is some mathematic formula to get the exact length of distance that ball joint moves using degrees and lengths shown but I don't remember it.
Second chart accurately shows distance ball joint needs to be moved dependent upon distance from spindle pin to center of ball joint pivot and degrees of caster desired to be added. top and bottom ball joints have to be moved accordingly to maintain spindle pin location. If you only move the top or bottom ball joint then the wheel is moved forward or back. if you move both ball joints the wheel stays in the same spot in wheel well. https://www.omnicalculator.com/math/rig ... side-angle