I found a generous local Jeep guy who let me have his old TJ springs for free. I used the rears because they are shorter to start with, and (I assumed) a softer spring rate since the front of a TJ is much heavier than the back. I did not want them overly tall or firm because I am hoping to get a soft top in the Spring and that will reduce the weight of my rear end a good bit. The two springs were roughly the same height, but I did not measure them. I started by cutting about this much off each spring to get them to fit over the top (metal) bump stop.

Then I supported the truck by the frame, removed the tires and let the suspension sag (one side at the time, if it matters). I have spring compressors ($10 pair from HF), and so it was a very simple matter of compressing them and putting them in place. I got about two inches of lift out of this mod.
Before:

After:

 

Gotta love the no-cut ZUK mod. I used TJ front springs cut to 12". Might be a little stiff but i'd prefer it to be stiff when empty and not sagging when I'm loaded up. Nice job

 

Good point, the front springs are not progressive and I am sure they provide a greater weight capacity. I am about to lose the hard top and lighten my load so the softer progressive spring was the one for me. I cannot even tell a difference in the ride.

 

And if you change your mind they're easy to swap out!

 

Are those 33 x 10.5 BFGs?