In these days it has been published a book about him, in italian language, full of anecdotes and a few games.
At this link:
"Il maestro dei maestri della scacchiera: Giorgio Porreca" di Achille della Ragione e Carlo Castrogiovanni
you can download the entire free pdf.
See also this web page http://scacchisalerno.arciragazzi.com/2015/05/05/il-maestro-dei-maestri/
These are some of Porreca's books upon which a whole generation of italian chess players has studied: