Don't know if you have looked at this site...
http://www.longacreracing.com/articles/art.asp?ARTID=13
The suspension AND rack design need to be coordinated to get the points to match the illustration at the bottom of the article. If you can't do that with your combo you need to go back to the drawing board.
I designed the front suspension for my van around a Corvette R&P. That is what I used as a starting point and then developed the entire suspension around those inner pivot points. Just slapping any old rack into an existing suspension will cause more grief then it is worth, as many of you have discovered...
Mark