Are Zippyy Joysticks standard bolt pattern for mounting (like a sanwa JLW or Happ) or are they a smaller plate like a Sanwa JLF?
The Zippyys are definitely not the same pattern as Happ Supers shown here.

This photo shows inserts for mounting a Super with a Zippyy on top.

If you turn the Zippyy 90 degrees, the mounting plate almost rests between the inserts.
Scott