Link 1 is to one of the bicycles that I have owned. That bike is of 1973 vintage and sports a very unusual set of head tube lugs. If your bike has Campagnolo wheels, remove the rear wheel and one of the hub lock nuts. It will most likely have a two digit date code such as 73. If that does not help, have a look at
How Old Is My Bicycle? and apply what you learn there. Best of luck with your project.