Question: 65 Barracuda Swaping from leaf to coilover what spring Rate?

Hello,
Just as the title says, I'm looking for a "ball Park" spring rate. I've ditched the leafs and straight axel set up. I have a set of Jag spring over shocks on the car for mockup/ build but now I need to get a proper spring rate on the rear.
The car setup is HDK frontend with QA1 coilovers, V8 with heavy over/drive auto, and out back I have a full XJ12 jag IRS setup.
The cars intent is mostly cruse and lively drivability, and the occasional road Rally

Thanks
j

I`ve got a pair of 350# , and a paqir of 500# springs for 12'' shocks , if u can use either of them ----