Hi, don't know if you're missing the caliper or that yours is past rebuilding but if there is one that will fit straight on,(CB400N or possibly CX500 but not sure about that one) its still going to be just as old and you'll be lucky to get a good one, there are engineering companies that make calipers for a price of course. Try wemoto.com 08450 292929 for caliper parts or David Silver Spares 01728 833020 Honda parts specialist.
Chris P.Duck
January 2011