There are two 27" sets on ebay right now. Cheap. here's one:
http://www.ebay.com/itm/Tandem-Wheel...item1c300c9681
The other was off a gitane with wolber super champion rims. Seller did not indicate that it was 27", but if it's off an old gitane, that would be 27", right?
Good luck.
__________________
The bicycle, the bicycle surely, should always be the vehicle of novelists and poets. Christopher Morley