I know he beat Gunboat Smiths *** and Jess Willard too, and he put in work on the great Harry Wills in a NC. Would Langford have just been too small for him? Would Johnson be able to clown him like he did to so many others?
If the 1923 sparring session (see Unforgiveable Blackness) is anything to go by Johnson would have won quite handily. I think that Langford would also have won against him. Far too able technically.