Sadly...most of the people that worked with him have already passed on, with a couple of exception like Susan Kohner, Eva St. Marie, Elizabeth Taylor, Mark Rydell, etc.
According to Sal himself in interviews and the new biography, he didn't like to be identify with his sexual preferences at all and would have liked it that way. For career reasons, I believe. But then I don't know. **shrugs**
It'll be an interesting movie, though. Sal did have flaws, like any human being there was. He had financial troubles even before and after his rise to the top. A very overbearing mother that used his trust fund till it became nothing. It was sometimes noted he couldn't pay his rent at all. Imagine a two-time Oscar nominee with money troubles. If you read further into his biography, it was very sad, but his passion for acting never left him. Even when his career took a nose-dive in the mid-60s, he still was willing to work.