While your replacing the steering box don't forget that you will probably need to rebuild the coupler while your at it. The shoes inside of it do wear from use. The rebuild kit is available at your local Dodge dealer pn 4443436AC.
As far as brake technology, the improvement over most of the stock stuff aren't huge. Although the obvious one is simply just the increase in size that comes from using 17-19 inch wheels. On technology, one improvment is going with 4 or 6 piston calipers. The additional pistons provide more consistent clamping force and feel compared to a single large piston. The performance calipers are now made of aluminum billet instead of cast iron, which doesn't do much for actual braking, but does reduce unspring weight, which is good. The other is newer lightweight hats that allow modular assembly of rotors. These are some what lighter, which means they are less effective as a heat sink, but they also allow replacing just the rotor when they wear instead of replacing the whole hub assembly. There also are brake pad compounds, but these can be bonded to old brakes pretty easily. Carbon metallic, ceramics, and other race type compounds are available for stock mopars.
Rack and pinion have an nice feel in a purpose built application, like AlterK or Magnumforce, but I haven't heard too much positive feedback on a simple rack conversion bolted to the stock K frame. Issues with mounting, clearance, turning radius and poor customer service after the fact seem to be the common complaints.
