Adams' Apple said: Ruh Roh....

Suspension alignment for a rack/pinion should definitely have more camber than normal. But they should have aligned it that way.
The only reason there would be a problem with the rack causing it to not self-center would be if the rack was BENT.
I'd be inclined to agree with the guys here that have that system, and say there may be a problem with the u-joint carriers....and the alignment.
Did they do the a-arm bushings and all?

 

Check the "phasing" of the u joints to make sure they are aligned properly.  I also played a bit with the location of the "U" joint on the end of the shaft from the steering wheel and found that helped  some with the binding but I also  found that the slightest adjustment in the "steering shaft support bearing" made a significant difference in how my steering felt.  My steering shaft fits the bearing with NO play whatsoever as it slides through the bearing.  I found that when adjusting the bearing it needed to be in a completly neutral position without pushing or pulling on the shaft which would bind the steering as the wheel was turned.  I snugged the nut on threaded stud  on the side of the bearing with my fingers and locked its position with some red loctite.  I then snugged the nut on the other end of the threaded stud  with my fingers and went for a drive, it felt good but needed tightening.  when I tightened the nut the steering was binding so I backed off.  The steering shaft is very tight in the bearing on my unit and there is no room for mis-adjustment.  The bearing has to be in a completely neutral position.  I ended up using thin shims on the bearing side of the threaded stud between the bracket and nut to adjust the exact spacing of the bearing.  When I tightened the nut with a socket the steering would bind until I got it just right.  I added a lock washer on the nut side of the stud.  I tightened the nut a little and when went for a test drive, tightened a little and went for a test drive.  Too loose and steering has slop, too tight and it binds.  I finally got just the right adjustment.  The nut isnt brutally tight but the lock washer has held it in place now for years. The black witness marks show it hasnt moved at all since I got it right.  The pics which are attached may make things clearer.. Good Luck, Chip

Alan