I think Mbj is a good actor tbh especially with Coogler movies so I think he brings something to the table, plus the synergy definitely doesn't hurt either between them.
I would say Hunter should be White because that adds to the character and makes it why he is the way he is. but they could go the route of making him the jealous cousin, following the route of Who is the Black Panther when S'yans son failed to take over, he could turn into the white wolf as his way of coping with failing to become BP " If I can't become BP, then I'll be the Wolf of Wakanda " and since then issue of hunter being white and not wanting to race bend too much, he could be half. Or if he becomes M'Baku then use it as either they are best friends and practically brothers, or they are brothers (since T'Challa and Shuri did seem to have another sibling) and he always was enamored with the mystical White Gorillas and so he becomes the white guerilla (Courtesy of Ture).
But i kinda want mbj to be a character that doesn't die in the first movie that's where being hunter would work because he can be an Ally to T'Challa and a Villain because his and T'Challas goals might cross ad they care about Wakanda first and foremost.