Thrilling forum

Found 2 more episodes of Giallo club (1961) first : (ep: I conti non tornano) (S4 ep:7) as Ciang
credited in cast list of radiocorriere Tv magazine, broadcasted on the 16th of april, 1961

and secondly Giallo club (1961) (ep: Il posto vuoto) (S4 ep:8) as Ciang credited in the cast list
of radiocorriere Tv magazine, broadcasted on april 23rd, 1961

He doesn't appear in the actual episodes, though. Only in the wrap-around segments together with the host of the show.

Apocalisse sul fiume giallo (1960) as Nightclub customer

Mondo balordo (1964) as Spectator watching women wrestling, which Boris Karloff's commentary would have you believe was filmed in the mystical east, but given Gregorio's presence was almost certainly actually filmed in an Italian studio (the actor on the right also looks familiar).

Fantomas minaccia il mondo (Fantomas se déchaine) (1965) in this sequel to the serie Fantomas movies, he plays a policeman at the scientific international congress

Ragazzi della marina (1958) credited as "Wu", as Singing south sea island matriarch.

An Italian speaker who can better understand the conversation may be able to come up with a better role description.

Akiko (1961) as Japanese tourist

Marco Polo (1962) as Chef of Tia Balena

La figlia di Mata Hari (1954). Gregorio has two roles here, the main one being a fairly large part as Prince Anak's trusted man (if he has a more specific character name then I missed it)...
...and also seen a very minor role as Japanese colonel