I've never heard of anyone doing it (that's not to say it cannot be done). It's probably easier to fit an Abarth 500 engine though, as the 500 and the Panda are closely related underneath their different bodies.
When you swap a engine like that, i would swap it into a new Panda 319.
It would be much easier to put a turbo or Rotrex on the engine you have then swap engines.