[Mike C]

Personally, I would do 4 springs. At this point, yours are at leat 40 years old, and they could use a break! As mentioned before, the lift you want won't work with re-arched stockers. Get an aftermarket 4" lift with rear springs. You won't regret it, and most likely, it won't cost all that much more. I originally did an add-a-leaf and 2 1/2" blocks in the rear, and I ended up bending the spring perches and making much more work for myself. The 4" springs in the front have been maintenance free since day 1.