The seller in Redwood City, who sold the NOS sets of magnesium Halibrand wheels also has what appears to be four (4) sets of
used and/or aged magnesium Halibrands for Cobras on eBay. I have no affiliation with the seller/sale of these items:
http://cgi.ebay.com/ebaymotors/HALIB...1%7C240%3A1318
http://cgi.ebay.com/ebaymotors/HALIB...1%7C240%3A1318
http://cgi.ebay.com/ebaymotors/HALIB...1%7C240%3A1318
http://cgi.ebay.com/ebaymotors/HALIB...1%7C240%3A1318
Caveat emptor, always. Good luck.