Despite his Anglo sounding screen name, he was one of the very few native (Italian) bodybuilders to achieve stardom in the sword and sandal/mythological muscleman genre. This also made him one of the few leading performers who was able to speak the Italian dialog from the script.
Footage from Kirk's film "Triumph of the Son of Hercules" was humorously used in a deodorant commercial in the late 60s, with Kirk flexing and boldly restraining horses during a chariot racing sequence. The female narrative softly says, "My brother works hard...he needs a strong deodorant..."
Twice subjected to the traditional "Test of Strength" found in sword-and-sandal movies. In both "Triumph of the Son of Hercules" (1961) and "Atlas Against the Czar" (1964) he was tied with outstretched arms between two teams of horses which then endeavored to pull him apart. In neither case did the horses succeed.