I have a 71 sedan that i want to lower and set level with the rear of the car in the back i have landrum leaf springs 125 lb with a 1.o longer shackle then stock with konis up front I was looking at some afco 550lb spring rate 5.0 dia spring 8.500 long or landrum with the same specs but 600 lb spring rate i will be running a 2.3 turbo with a t9 .