...and it seems pretty much level front/rear when it's in the middle of that range, so that means if "stock" is level, then it can go a couple inches either way. As stated near the beginning, softer bars will give less range, unless they're in a lighter vehicle. If you want to know exactly how much less, look at the ratio of the spring rates.
CV joints are not much affected by gravity, so they don't care how much you raise or lower your vehicle or whether the previous owner did it or how much higher or lower it is in comparison to some arbitrary "stock height". CV joints are affected by angle. If you jack the front wheels off the ground and observe the extreme shaft angles, that's what breaks them offroad. If you look at the shafts sitting at normal ride height, this is the angle where your day-to-day wear will occur. If it is straight, the CV's will last. If it is not straight, they will wear faster. How much faster depends on how much they're not straight. It's not like a 1-3/4" difference will wear as slowly as a straight shaft and then at 2" it just suddenly wears out in 100 miles! The more angle, the more wear. Besides, that height/angle goes all over the place as you drive. At either height, the CV's will be bending to all diffetent angles as you drive, it's just that the more you lift or drop it, the more angle they have to deal with. So... If you're worried about how lift or drop will affect your CV's, forget about fender height. Forget about "stock height". Forget about whether it's been