To put this simply i am looking to move the motor back in a race car approx 20" keeping the motor height the same. i am curious what would my new spring rates be without testing? approx 1g corners. about 550 lbs moved back.
Do you know the current weight distribution?
If so you can roughly model the shift.
Unless the car is very light (which I doubt with that heavy of engine) the change may be negligible.