Brilliant adaptation! For members without access to a machine shop, you can use Osborne pins in Handy Jr. machines -- easy swap and can be switched back with no harm done to the machine. The new pin threads will accommodate any "1920" *** die (snap, grommet, rivet, etc.), but die shanks will need to be turned to a slightly smaller diameter to fit Handy Jr. machine bases.
*** Osborne is a "1920" machine (as are standard C&C Metal, Dynaline, Wade, and Defiance machines... which unfortunately are all out of production, but still around).