What's a shackle plip?
What kind of rig is this for? Subs, K5s, longbeds, 1-tons, 1/2-tons...they all have different weights and are going to need different spring rates. If your shackle is almost vertical right now, flipping it over with no other modification is basically a 4" lift.
Basically, measure the vertical distance between the two eyes of your shackle before it's flipped. That will be how much lift you get. My K5 ran 5 leaves plus the overload stock. I don't remember what the angle was, but when I flipped it, it sat about the same as the front, which were about 4" lift springs.
Remember, if you remove leaves, you not only lose height from the arch of the spring, but also the height of the leaves themselves. Overloads are about 3/4" thick, so pulling an overload out is going to lower you 3/4" even if it wasn't helping your arch to begin with.
Swapping from a 52" to a 56" directly will actually lower the truck a little bit if the packs are the same thickness and spring rate. There is no special formula for how many leaves to run or how much lift a 56" or 52" from xx truck with give you. There are so many different GVWRs and weights between subs, K5s, and pickups, that it's just about impossible to simply say that "6 leaves from springs from xx truck will give you xx lift on xx other truck".
gl
