I'd also opt for the hope No2 caliper ,in that it fits any frame.
You can attach the caliper to the stay via a clip rather than the torsion arm you see in big.ecks pic on his worldfarce
the short axle and all the bits are available,the only thing hard to find is a thin end spacer[4mm] instead of the standard one on the hub.
I know i sold a spare one to someone here so im sure they are about if you ask :?