i have researched my gizzi line in italian records and church records. i too have come across the same issue, frequently gizzi and izzo are used interchangeably in the church records especially. not a big deal, look for both spellings. they mean the same - from or out of egypt.
my great-great grandfather was also named raffaele gizzi, born in 1837 in gioia sannitica, family originally from civitella. the oldest relative i have found so far was born in 1693. unfortunately for me the church records for the period prior to 1780 have been lost or destroyed from their parish. notary records have helped some. i wish you better luck.