The frame's images show the fastback seat stay treatment of the Team 3V. Those were reported to be built under contract in Italy, but not by Masi of the Vigorelli just made for Masi USA.
A true Masi? Let's say yes, as Masi was still getting royalties on them. However, while they had a Faliero Masi signature applied to them, going by a very old post from Brian Baylis about Faliero's opinion of fastback seat stay treatments, at least how Eisentraut did them... Faliero would not be happy with that seat stay feature.
To confuse things, Alberto did use the fastback seat stay treatment elsewhere later.
I have two 3V's, both ride very much the same.
John Jorgensen
Torrance Ca USA