According to CampyOnly (which of course is NOT gospel) the Porta Catena was introduced in '79... that's pretty strong evidence for a post 78 production of the frame.
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1 Super Record bike, 1 Nuovo Record bike, 1 Pista, 1 Road, 1 Cyclocross/Allrounder, 1 MTB, 1 Touring, 1 Fixed gear