1967 Cuda FB project

No idea how they would compare, but for what it's worth my 04 Viper with aftermarket coil overs has 800 lb/in rear springs and 500 lb/in front springs and weighs 3200-3400 with me. Damping and weight balance has a lot to do with that though. The factory rates were something like half those numbers, but with different damping. Suspension travel and application will also play into that.