There's a series of wiki pages on the Dukes of N(e)apoli . For our timeline you can begin
here .
Until 1137 Neapoli was ruled by Greek Dukes .
The last of the line was Sergios VII who died on the field of battle , heirless , against the Normans of Apulia . His alliance won the battle but his death marked the end of Neapolitan autonomy .
The source for this information is John Julius Norwich ( as it is stated in the pages ) , who I think counts as "legit enough" . Also , I am very fond of his writing style .
Can't really say if the name of the Dynasty was Spartenos , but at least we know there was a Greek Dynasty there at the beginning of our timeline .
So yeah , GO SPARTENOS !