As much as you can get is what I have read. I bought this Tenhulzen alignment system. It is a couple of plates with some stand offs to touch the wheel rim, not the tire, and it comes with a digital angle meter. I have aligned my 72 Charger before using an angle meter app on my phone with some straight edge steel. The Tenhulzen is much easier to use, and a little more accurate. https://www.wheelalignmenttools.com/product/2-wheel-alignment-system/ On the right side there is plenty of adjustment. I have the caster at +4.8° and the Camber at -0.5° On the left adjustment is limited. The best I can get is caster +3 and the camber at -0.5. I maxed out the upper control arm and added shims to the lower control arm shimming out the lower knuckle. With caster maxed out now I get closer to the other side, +5.0 caster, with -1.95 camber. I know, camber way out of spec. No way can I get the same caster on the left side as I get on the right and still have -0.5 camber. I have a pair off off set upper control arm bushings coming for the left side. I set toe to 1/8" toe in and drove the car like this last night, with that much caster it drove great. No wander, precise steering and easy centering after a turn. Back to the question, how much caster is too much?