I went through the same thing last year. The previous owner had put lowering springs on and the tires rubbed, I bought a new set of springs and it sat way too high, I then cut off one coil and it sat too low. I then discovered the springs I bought were for a convertible not a coupe, they made them stiffer because of the 'cocktail shakers' the convertibles had. I bought another set and again it sat too high. After taking them out I noticed the part number on the springs did not match the number on the box, back to the store once again to get the correct springs. They now keep the car at the correct height. I'm getting good at removing and replacing the coils I may even buy a spring compressor.
I may be able to find the part number if you need it.
Good luck!