Well, the beauty of the 312 setup, is that you can bolt the carriers, discs & pads straight on using your existing calipers, thus saving the need to mess about bleeding the brakes/changing the brake fluid etc.
I've done a few track days, & have always been a firm believer in uprating my pads but running cheapo discs (I find that the drilled and/or grooved discs only wear the pads out quicker!). I'd go for likes of Ferodo DS2500's/Mintex/Pagid pads.
The bigger brake kits (including the R32 setup) will cost you a fortune & also the extra forementioned hassle.