you could try the re-arc method but I have found the springs break after some use when re-arced. especially old springs. you may be better off to remove a leaf and see how it affects the stance. once you have it apart the first time it will be easier to do in subsequent dissassemblies if you don't get the required affect. you will need some new center bolts that hold the pack together. remove a leaf and assemble. set the truck down on it and drive it around the block or down the country road. allow it to set itself. then check the ride height. if it is how you want it then replace the ubolts and torque them again after a few miles of driving. torque them with the weight of the truck sitting on the springs.
if you don't like the height, dissassemble and remove another leaf or whatever you need to do. don't remove the springs from the truck, leave the main leaf attached and work from there, way less work. take the smaller leafs out and leave the main top leaf and the one directly next to it. this would also be a great time to install some of those teflon strips that go between the leafs to keep them from squeaking. newer trucks have them. standens could probably set you up with the parts you need as long as you know the head diameter of the center bolt, the shank diameter of the center bolt and the length. if you dissassemble it you can take the old parts, including the u bolts, with you so they can match them up. they can custom make any size of u bolt pretty well.
if you have to remove quite a few leafs to get the ride height and ride quality you like I would then recommend you install a longer "overload" style spring at the very bottom. this allows the other springs to move up to a certain point and then they contact the overload leaf and the pack becomes stiffer. it would stop you from bottoming out possibly. especially on the rear of the truck. the link is just a pic so you can see what I mean about the lower spring. you could also get that leaf in a thicker design to compensate for too much drop or install a spacer in the right spot to get the ride height you want.
https://www.truckspring.com/products...43-1263HD.aspx