Hopefully White Wolf won't be in this AT ALL. God I loathe that token white boy
And as far as Kilmonger being too big, You won't find TOO MANY 6 "7" 300 pounds of solid muscle actors out there who have the acting talent (and let's face it, hype) of MBJ. Black Widow is supposed to be a Russian Assassin and she's played by American Scarlett Johannson (not even with a HINT of accent)
Thor is supposed to be 6 "8" and is played by 6 "3" inch Chris Hemsworth. MJB is only 5 "11" but he can certainly bulk up (as proved by Creed) amd he has the talent to play the intellectual equal of T'Challa. Plus Kilmonger is the sort of person whose charisma allows him to easily manipulate and lead people, and we all know MJB has that in spades. He can do Kilmonger justice.
Told the doubters a long time ago