William VIII's first wife Marie de Foixe dies younger than historical (1467), freeing him up to marry a daughter of his ally Francesco I Sforza. As the marriage happens earlier, he gets to marry the elder daughter Ippolita, as opposed to her younger sister Elizabetta. The death of Francesco's sons without lasting heirs would leave Milan to William.
Their son, Duke of Milan, might then marry the Infanta Isabella of Naples (in this TL the daughter of Ippolita's sister Elizabetta) and make good her claim to the throne of Naples.
Their son in turn might make an interesting husband for one of the daughters of Ferdinand The Catholic, perhaps Isabella or Juana, with the possibility of the Paleologus inheriting the newly united Spain, or at least staking a claim to portions of the Spanish mediterenean empire, or perhaps inheriting Aragon in opposition to Philip of Burgundy in Castille.