You may never know exatly but alot of people use pre-post Tens Speed Drive imports (TSD) as a way to date them. TSD was an importer of Guerciotti for awhile. The frames were built in Italy by Guerciotti and shipped bare to TSD in The States where they were painted and decaled.

Your guesstimate on date is probalby close, it has Campy portacatina dropouts and braze-on front derailleur hanger.