Garret James,
Without having a surviving carrier of your GrGrandfather's y-Chromosome, it is difficult to discern much in regards to his specific line's ancestry, but finding a pool of other Italian Vitalis who have tested may be helpful because their genetic signatures could be compared with the broader Jewish population.
Kevin,
Greek Jews? Italian Jews? I'm really not sure there is such a thing in truth. But there is such a thing as an "Opportunist Jew" (but opportunity seeking isn't exclusive to the House of Jew-dah). The Radhanites, medieval Jewish merchants, were very active all over the Mediterranean Sea (including Italy), yet Jewish migration/relocation has not just been driven by commerce/opportunity. Jewdah has frequently been expelled from and invited to various nations/kingdoms for the last 2000 years... which is why I think Hg.J is so wide-spread around the Med. Sea and Europe in general. So, finding others with your genetic signature may be the most informative. Have you submitted your results to YSearch.org?
Kind regards,
Hanok
