I just received this email from my friend and well regarded Semitic language expert Ruaridh Boid of Monash University:
The Greek Iona corresponds to Hebrew Yona yod vav nun he which is a diminutive. But as I said yod vav nun COULD exist as a diminutive of either name but is not attested.
Well folks, that's good enough for me. I am officially starting work on my next book which (among other things) the kabbalistic system developed by St.Mark for his gospel based on the information that Irenaeus gives us in Book One of his Against All Hersies (or Refutation and Overthrow of Knowledge Falsely So Called). My only question for Boid is how Iona would be distinguished from Jonah before the fifth century (when diacritical marks were first used). In any event, the book is now a go. I also received an email from Harry about the underwater investigation in Alexandria which I will publish shortly.
Stephan Huller has had a life long interest in religion and spirituality 
dating back to conversations with his grandfather, Gaston Frank. "He said we represent one of the last descendants of the Frankist Jewish faith in the world," he muses. "I grew up thinking that our family was something like the Last of the Mohicans."