Holy smoke batman, have you been riding that thing too fast lately
Is the whole thing knackered? I spose the heat has welded the pistons?
I have no idea whether the rear caliper off your 900ss would fit and you could take it off that, but it probably won't other wise you'd have thought of it. You could always take the SS to Congleton of course, but you should be able to find a caliper from somewhere, got a couple of weeks. If you need me to give you a hand, give me a call.