You COULD take springs out of the pack, like the bottom "overload" spring, for example... That WILL lower it - plus the cost is.....nothing? Got that much to spend?
2wd hangers will make it lower. 1/2 ton springs will make it lower. There are many ways to go about it, but you are not likely to find an "off the shelf kit" to do it - i've never heard of one. You're gonna have to make it up as you go.
If it were me, i'd remove the overload springs and get that fast inch. The bottom most spring...Then I would spend time considering 2wd or 1/2 ton hangers. I'm pretty sure they sit higher (lower). Shackles?
Are drop shackles not an option?
The spring length and width are important to consider, regarding. Probably not so much length, but some are different widths and those hangers would NOT be interchangeable..
This will require new shocks?
Check u-joint and drive line angles, or whatever. (Safety first!)
Mind you , it probably is different heights front to back. (Lower in the rear.)