You can measure the radius of your axle, the thickness of the perch bracket on your axle and the spring thickness. This is how much your lift will be when those dimensions move under your spring. You will probably be in the 5 1/2 inch area. I think thats about what mine was. I also went with 16 wheels and lt tires for about another 1/2 to 3/4 rise. Now I need to buy 30 inch stabilizers for the rear and build a new step box as the first step is too high.
You may also have options with your shackles or a true track kit (?) It's a kit used for axle alignments but I think it gives an inch and a half or so of rise. It's been a year so I'm not sure of the name. It's sometimes a little too much with the flip and not enough with the other tricks. Some guys also build a subframe to hold all the brackets and get 2 or 3 inches.