Who are you, and why would we want to or have to prove anything about Bruce Lee's fighting abilities to you?
Either you believe he could fight or not based on what is available today as evidence (video's, personal recollections, books, personal journals by Bruce). I could care less what you believe about his abilities, as I have my own thoughts based on what I have seen. IMO he could fight at a high level. He was not unbeatable for sure as his chin could be taken into consideration and his back injury too, but to exploit those weakness would not be easy to do. Do you think you would have been up to it lunghushan?
James