If you got coils, I would spend the money, stick with the coils.
I am going to swap out my leafs with coils real soon. 

If you do swap to leafs in the rear just cut off the coil pads and buckets from the axle and frame, weld on new spring plates, get the springs and then mesure it out where the spring mounts need to go and weld them in.

 Doing this and you might as well run a u- bolt flip kit, some johnny joints, and frenched rear spring hangers. 

But i would stick with the coils and 4-link it.       IMO=