[Birkin7]

I'm working on my girl friends rig. I have 3 linked the front and will be 4 linking the rear. I need to start thinking about spring rates. The vhecile has 5" up travel and 9" down travel. The vehicle wieght is 4200lbs about VERY CLOSE. So what spring rates should I'd be looking for? I'm a race car guy. I use about 450lbs springs on a 975lbs car with a 2 to 1 motion ratio. I have know Idea were to start please help.

Thanks
Larry