At boxing?
Let's see... Ali was a typical out-fighter, closing up his body and using his superior speed and reach to win. And trained boxing every day of the week.
Lee trained many arts, in many dimentions. While his pound for pound power was amazing, it's still nowhere near the punching power of a pure world class boxer weighing 100lbs more than him. Add his shorter reach to that as well.
Conclusion: Lee would probably not even get 1 clean shot in, and even if he did, it would never have the knock-out power to hurt a guy like ali. If Ali can keep Lee inside his striking range but outside Lee's with his legendary jabs and movement, he would never get in trouble. Actually, most world class boxers would never get into trouble vs Lee.