late to the party, and not much to add, but I can say that Mondia Specials in the early 70s appear to have come from the factory with Atom 14-28 freewheels and those all seemed to work fine. Most people who ran this kind of lash-up understood that running your 52 with your 28 was a very bad idea, and I, for one, set up the drivetrain so that other gears were reached more quickly and easily, but the 52/28 was unattainable.
The Nuovo Record derailleur just wasn't made to worth with that kind of wide-ratio gearing. It can be done, but why? Why do it, when the derailleur will work so much better if you set it up to work with everything but the 52/28 combination?
Nuovo Records work best with tight-ratio freewheels, what they were made for. They shift as well as Ergo stuff with that kind of freewheel. As a practical matter, these days, 14-26 is the biggest freewheel I'd run with a Nuovo Record derailleur.
Charles Andrews SoCal
Anyone who believes exponential growth can go on forever in a finite world is either a madman or an economist.
--Kenneth Boulding