I took a huge dump today that was a striking resemblance to MLK. Perhaps you could do a claymation of MLK with it? Just find some crackhead for the voice over.
Coincidentally, I unloaded a particularly meaty porcelain buster this morning, complete with a couple of large, undigested beans - a truly imposing hunk of excrement which bore an uncanny resemblance to Jesse "Breadbasket" Jackson...
Taking a more practical approach, if You wish to obtain funding it's best to adhere to the Hollywood custom of casting a Jew in the lead role. Now, we require a Yid who possesses the "gravitas" to give such a "serious" character due justice. Hmmmm, let's see... I know! How about Jack Black? Looks and physique in a single pot-bellied package!
Sure, Black's hairy hide lacks the melanin levels to live up to his name but that's nothing a bit of "makeup" can't fix - especially if the "makeup" is liberally applied with sturdy work boots and an old cricket bat. Fifteen minutes of good, solid "preparation" and fatso will attain a bluish black hue which shall last for the duration of filming...
Mind You, You could even emply a genuine Negro: I'm confident that Koko B Ware would appreciate any work You could sling his way:
If negotiations with B Ware were to break down, perhaps that fine black thespian Ade is available for hire:
I suspect, however, that the expenses associated with feeding the fat prick (in addition to installing a reinforced steel toilet on set) may blow the majority of Your budget...