Someone posted a while back about fitting a Fireblade/SP1 rear calliper to their MC21 because they wanted the gold, bling bling look.
Well I'm here to tell you that they are a straight swap. Had one from a 2002 CBR lying around, so out of curiosity I bolted it up this weekend and it fitted great. As far as I can see it's the same calliper only GOLD.
Sorry but I took it off without taking any photos, but it isn't that hard to imagine.
Might be worth going round all the other bits in my garage to see what fits.....