I've asked a few suppliers and Hispec is able to supply rotors and bells to suit. The only thing I don't know yet is what the price would be. But I can imagine this would be a nice upgrade for all 4x4 cossies. Perhaps if there is a lot of interest they could supply a kit. The rotors I would be using are 335x32mm.

The main problem on the 4x4 is the low disc offset which means there is basically no room for a 4 (or 6) pot caliper unless you have one of the few wheels that provide a lot of room. These calipers are of the sliding type, meaning you only have the brake pad and a relatively thin metal part to hold the brake pad outside the discs surface. I think they stick out about 4 cm of the disc compared to 6 cm for most 4 or 6 pot calipers.