It looks a though you are budget conscious so the easiest and cheapest would be to turn the factory springs 180 degrees to center the axle tube in the wheel well and weld perches on in the right place. Get hold of a BFH and allow more time that you figured for switching the shackle pins and spring eye bushings. An extensive knowledge of cuss words and a cold beverage helps. We have a press which takes most of the fun out of it. If pocketbook is healthy I like coil overs for a both good and stable ride but this means a lot of fabrication by the time some type trailing arm (4 link/ladder bar) and a Panhard bar is in place. We have also used the Lincoln/Corvette/Jaguar independent rear suspension which gives a truck that can run autocross.

Evan