Eaton spring has the correct springs for your car:
https://www.eatondetroitspring.com/findmyvehicle/
Coil Spring Specialties will make what ever you need:
https://coilsprings.com/default.aspx...SAAEgJ-QPD_BwE
I had CSS make new spring to replace the brand new 'correct' springs for my GTO after I learned that 'correct' springs gave my GTO the original rear end lower than the front look that was 'correct'. I asked for .75" over stock and that is EXACTLY what I got.