Things to look for and that are present on the purple bike you are looking at. It has Campy dropouts, and they are the old style, 1970's. Hard to see but the way the stay and fork ends are finished is different from bike to bike. It has a chrome fork crown and it looks like a nice one. Curve of the fork. Italians seem to get a graceful curve. Clearance at the seat stay bridge and fork. On the bike i question it looks like larger clearance as what you would find on a 70's bike. Hard to see the lugs. Seat cluster and how that is finished.

That's the stuff I look at.

The bike you linked to is a real nice looking bike and well equipped.