1965 50n smallframe fuel tank needed to complete project

as topic says, having trouble finding one, they are smaller than the 50 special, does anybody have one lying around? or can suggest a tank from another bike that i can modify to fit?

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=110236392505

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=250229285790