Have you considered swapping in a steering box from a Jeep Grand Cheorkee?
You can put in a 93-98 GC box either rebuilt from a part store or from a salvage yard. You then need a new rag joint and some cheap fittings (which can be found here,
http://lee-powersteering.com/rebuild-misc.htm )
Can be pretty cheap if you do the salvage yard route or maybe $150 if you buy from part stores. All-in-all, it provides a much more firm steering feel which helps when you are at highway speeds.