Scrap,you said you  know William Cheung,I think you would be better off asking him than  karate men.
After all he grew up with Bruce.They both trained under Yip Man when they were teens.They both fought from what William says in the streets of Hong kong and in some local back alley match ups and also against some British soldiers in local boxing matches as well from what I heard from William.

Some people care  what tournaments someone has won and some dont put credit in them.
You cant surely measure everything upon them?
I know it is how the physci of this century has turned out but
even some karate masters from older times would themselves avoid public competition just on higher spiritual disipline reasons and would view it a personal loss and an ego trap even if they won it.
Yip man had no trophys,William had none from what I know but we also trained some world open kung fu champions through that lineage.

This would serve the purpose more:

Ask your karate friends who would win out Ali and themselves in a no rules match  ,i bet they say themselves,cause they would just break the first set of toes or the leg he put forward.
If it was to boxing rules only Ali would walk it in .