These are on Ebay, with about 2 hours left, and no bids. Thanks, Jeff (zman) for finding this. The rear master cylinder looks good - wish we could see the inside bore...
https://www.ebay.com/itm/111333586737?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
https://www.ebay.com/itm/111333586737?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649