I like it lower. Personally I find a way to make it functional. Maybe not the opinion you want to hear. But if you plan to carve corners..... lower is better.
Thanks for all the help so far guys. I heard from the builder and the Mustangs Plus 620s are what is in the car. We are going to try a stock spring and see what happens. I will try to keep the Shelby drop in place if I can, and may consider changing the tire width if I have to.
Again, any other ideas or suggestions are much appreciated.
I have read that 620# springs are too much for a well balanced car. If you are going to be replacing springs I would look into the progressive rate springs from Dr. Gas or pro motorsports whichever they go by.
But if those springs are new 620's get the 1" pads and see if that would fix your problem