7/5 would be nice as long as you have some sways to go with it. That way you can play with compression/rebound and not have to worry about not having enough roll stiffness to balance it out.

I will say the best my car ever rode personally was when I put the ES upright bushings in and they were fully greased. I still had the 8/6k springs and it was way smoother than it is now even with the softer springs. But now that they're pretty much out of grease they suck, which is why I really wish my sphericals would ship already.

I figure 6k/4.5k springs, progress bars all around and an entire spherical rear suspension the car should drive pretty damn nice. Even with sorta over stiff JDM shock valving.