My 1971 Italvega Nuovo Record build is proceeding, and for headset installation I used a length of threaded rod, washers, and nuts to press the headset bearing races and cups into the head tube.
The photo shows both regular nuts and wingnuts at each end, however this was just how I assembled the parts before purchase, figuring I could decide later which worked. In the end, the wingnuts look better, but functionally I think the regular nuts worked better, as the cups fit tightly and are difficult to insert simply using hand strength with the wingnuts.
The tool worked well, and allowed me to install my headset without damaging anything.