Gaz and Listers,
I googled Guarini and found nothing cycling related. I did learn about the 16th century composer, so all was not for naught.
Perhaps it is a store brand frame? Many fine frames were store brand Italian bikes built by BMZ, Billato, Gloria and other even smaller shops (the histories of which I would love to see recounted on this list).
I have a wonderful BMZ built Lazzaretti ( http://farm4.static.flickr.com/3089/2320860647_eeaa9d134d.jpg) that is my daily rider and list member and BVVW member Norm Hellman has a gorgeous one too.
I think there was alot of rebranding going on in Italy from the fifties through the eighties. Whatever yours is, she's beautiful.
Harry Schwartzman Brooklyn, NY
Shameless plug: http://www.nybikejumble.com.