AFAIK Red/Whites are RRC heavy duty, the "police spec" springs. I've fitted a couple of sets aand they do seem to lift a RRC about 1", though of course any new spring will put a bit of air back under the car.
Yes they are wallowy :-k I never got the impression thay were a lot heavier and given that a Disco has no self-leveller and a higher loaded rear axle weight I think they may not be enough.