This is how I do it, I posted this in another thread, so I just copied and pasted it here. I hope this helps.
What I do when taking leaf springs apart is use 2 "C" clamps to hold the springs together, 1 on each side of the center bolt. After I remove the center bolt, I replace it with a long piece of all thread, about 12" long, 2 flat washers, and 2 nuts. If you have access to a welder, weld 1 nut to the all thread to make it a bolt, or double nut it. Once the all thread is in place, and tightened down, remove the 2 "C" clamps. Now you can start loosening the nut on the all thread until the tension is gone and the spring leafs are loose. You can remove the all thread now. Once you figure out how you want to stack your springs, you can use the all thread to put them back together. When the springs are tight, put the 2 "C" clamps back in place, remove the all thread, and put the center bolt back in.
I just finished lowering my 87 B2000. What I did was removed the leaf springs from the truck, disassembled them as described above, flipped the main leaf over, and installed 2 additional leafs for a total of 3 leafs, plus the overload spring. I then used a 1" block. This is how the trucks sits now.
I'm running 235/75/14 tires on the rear. I have about 1" of travel before the rearend hits the frame. It rides good. I've been doing it this way for years without any trouble. I'm running 195/75/14 tires on the front. I think the front needs to come down a little bit more, so I'll be playing with the torsion bar adjustment. Maybe lower it another 1/2 inch.