Radio Times (UK TV & radio listings magazine), 14-20 August: "DID YOU KNOW? Sylvester Stallone was originally to be called Tyrone Stallone in tribute to actor Tyrone Power".
They almost certainly got it from Wiki: "Mother Jackie Stallone was a fan of Tyrone Power and had originally named him Tyrone Stallone, but when she got the birth certificate it had been changed by Sly's father Frank Stallone to Sylvester Gardenzio Stallone."