XJ v/s ZJ rear suspension?

I will be getting a XJ when I return from deployment in a few months on a Carrier (leave in a few days), and am thinking about all the mods that could be done to the Jeep I haven't even met yet.

So my question is based on the differences between frames and rear suspensions of the XJ and ZJ. Are the "frame rails" (unibody, of course) approximately the same? If so, could a ZJ coil spring setup be reasonably easily grafted in as a cheaper conversion to coil rears? I was hoping someone would be familiar with both and easily answer as to whether a PnP ZJ donor could be grafted into the same unibody to provide added flax and travel of the coils springs, along with a 3" lift easily by using the front coils? Just a thought. Any input or suggestions? Even if the answer is "no way, it would suck and makes no sense"... thanks for responding.

The ZJ rear axle is crap in comparison. If you really want coil/coilover in the back a custom setup would be the best.

Not done it, always seemed a waste of time and money to me. I'd just get a ZJ, if I wanted coils in the rear.
The spring perches would be the easy part it seems to me. Getting the control arms and trackbar right would be the difficult part, IMO.

there is no "reasonably easy" when it comes to completely removing a suspension system, and then installing a completely new one. especially when you are trying to mimic the new one from another vehicle. keep your leafs, or do it right:
http://claytonoffroad.com/product_info.php?cPath=18_66&products_id=107