Well, I haven't had much free time so the project has kind of stalled out.
I am not totally sure this will work either. Basically if you strip this front crossmember down to just the crossmember itself you end up with something that looks very similar to what you get when you buy a a crossmember from an aftermarket company. The A-arms, spindles, coils, etc, from a Crown Vic. look like the same as ones used on a Mustang II, although they are, I'm sure, not the same dimensions. So I think a MII rack may work.
The upper pivot point and the inner piovot point have not changed. I agree, the instant center point, by narrowing the crossmember, will be closer together in relation to the opposite side, hence the narrower rack (MII as compared to a CV).
That being said, I may end up just scrapping the whole idea and going with an aftermarket system.
I should also add. I am not an engineer of any kind, I do not recommend that anyone do this modification. It is only an experiment and all material, photos and dimensions in this thread should not be used by anyone but trained professionals. Do not try this at home!