Morgan,
Easily, the best advice to give for Mustang suspension questions is to refer to the "Bible", Mustang Performance Handbook 2 (Chassis), by Willliam R. Mathis. One book deals with engine and drive train...it's not the one you need. First edition was 1995, and it will explain the problems associated with the design of the Mustang. A thorough understanding of the limitations of the compromises used by Ford will make the system work much better.
Many solutions offered in the book will be beyond the rules that most IT and Solo people are stuck with, but it will give you paramaters to play within. It gives designs, and dimentions of parts to make your self.
Most off-the-shelf parts are for the GT, and don't work with the base 2.3, so read before you spend.
I've set up two M3s for ITB, and of have ideas that we never put to the metal. There was still more room for improvement.
Good racing.
Bill