Stanfa was definitely involved in the Bruno hit. After the hit, they had police protection for Stanfa while he was in the hospital, one of the officers reported that Stanfa was visited by Sindone & Salerno, and that they were speaking in Sicilian with each other. After he got out Stanfa was spotted by surveillance with Tony Bananas in NY before he got clipped. Leonetti says in his book that once Bananas got whacked along with his brother-in-law, the Genovese soldiers went back for a guy they believed was Nicky Scarfo, Anastasia says years later that guy was revealed to be Stanfa, through informants.

Stanfa was definitely saved by Carlo Gambino and his family, Stanfa had some sort of deep Sicilian familial connection with Carlo, and he vouched for him and saved his life. I read it was Castellano who also was the main reason why Stanfa was named boss when he finally returned to Philadelphia.