
Having done considerable research I determined that our boxes are actually pretty nifty and rather unusual in some respects. The key feature I decided I wanted to keep is the 16:1-13:1 variable ratio; most of the performance boxes I could find were fixed ratio at 12.7:1 which would make parking lot steering much less pleasant.
The key areas I am looking to improve are on-center feel and significantly increased effort. There are several options available to us; virtually any Saginaw box from any GM car will fit with at most a few modifications, however, there are a myriad of boxes with widely varying properties out there and it was not clear what would work best. I want a slower ratio near center as the car tracks incredibly well with very little input, and I want to improve the feel.
After looking at all sorts of boxes from cars like the 88 Monte Carlo SS or the 96 Impala SS along with aftermarket boxes from the likes of CPP I called Lee Manufacturing (I read about them in an old Car Craft article on Steering Box upgrades) to ask what they could do for me.
Given the unique properties of our boxes I think I have decided to send in my box and pump for rebuilding. One nice thing they will be doing for me is to add an inlet to the pump for my Hydroboost unit. This is somewhat more desirable than the TEE fitting I used for now.
Total cost for the box and pump rebuild along with the tweaks needed to update the performance is somewhere around $500 or so. If it results in significantly improved feel and control it will be money very well spent.
If you go with a remanufactured box from the local parts store you can save quite a bit of money but until someone does this it is a bit harder to be sure which one is the best for our cars. One factor is the total turning sweep; I definitely want to preserve the total turn angle and it was not clear which boxes will do this properly.
http://lee-powersteering.com/index.htm
http://www.carcraft.com/techarticles/ccrp_0901_gm_steering_box_upgrade/viewall.html