I believe the KW DCCs that he has already have the standard 60mm springs, so you might be able to just check out any spring manufacturer (Eibach, Swift, etc.) for the right spring rate and length.Depending on the travel of your rear struts, you can look into something like the Ground Control Coilover Conversion and pick any height of 2.5" springs you want for the rear. It'll also allow you to tinker with spring stiffness. I did the same with my Fortune Auto 500's. It allowed me to use stiffer springs in the rear than what FA provides. Same principal can be applied with trying to adjust your ride height. It'd also allow you to fit things like helper springs.
Another option that I've been thinking of are these:
Not sure if they will just drop into place though.