Does this front end have dropped spindles? You need to look at the upper spring pocket and see if it uses the flat upper spring end, which it probably does. Afco and Eibach both make a huge selection of spring rates for the 5 1/2" and 5" coil spring with one end ground flat. If you have dropped spindles you can replace with a standard spindle and gain about 1 1/2". Are the lower control arms level and parallel to the ground?