An interesting question.
As you point out contemporary versions of yesteryear confectionary is often a different size so original machines can't cater for what's available today.
From my point of view I'd be facing the question "Would I want to remove part of the mechanism from my 1940 - 1960s machine and replace it with a non original part?" It wouldn't take me very long to decide against doing that.
I know it would make the machine more effective today, but how many car enthusiasts would add ABS or reversing sensors to a Ford Model T for basically the same reason?
Somebody well known to us tooled up to manufacture modern allwins in China and imported them 20 odd years ago. Modern coinage and in the case of a vendor, modern mints. There was a short flurry of interest but not enough to keep it going.