When I upgradeed to the 312mm setup I didn't know that the calipers were the same so I went the whole hog and done discs, pads, calipers and carriers along with upgrading to HEL braided hoses. (Would have been rude not to as I got the whole setup for £42)
You will obviously need 312mm disc and pads to suit, I am gonna go for EBC Greenstuff pads when I need to change mine. Other people might have other suggestions for pads/discs.
Sorry I can't help you with the part number. I reckon you will get them cheaper from a breaker's or ebay. They are quite a small part so hopefully breaker's don't realise the potential of the part and sell them off cheap.