I'm very glad the overall tone of this thread is sarcastic b/c this question really can't be taken seriously.
Bruce Lee was a phenomenal athlete but sheer size alone makes an easy win for GSP, not to mention gsp's ridiculous wrestling advantage.
But Brock Lesnar would totally take them both!! lol.
Size meant nothing to Lee. The man was built of stone. He overdosed on a drug because he had no body fat to absorb any of it! Lee was said to be one of the strongest men P4P in the world. I dont think GSP having 20 lbs on him would mean anything to be honest. And who said Lee didn't grapple? Have you seen any of his sparring Vids? His akido was amazing.
I would give it to Bruce Lee if he was 25 pounds heavier and if he had some time to train in MMA. Otherwise, I'm going with GSP.
You seem to miss the fact that JKD is one of the precursors to MMA...