This would either work beautifully, or inadvertently create something so offensive that the show could never be produced again, but Donald Glover (or a Donald Glover type) as Finch in "How to Succeed."
The "Brotherhood of Man" number is built on a staggering number of racial signifiers and innuendos that, with a black Finch against a bunch of white company types, would either be an intensely dark and satirical look at trying to break into the boys' club, tokenism and racism in big business... or would play as a minstrel show. I think a white Finch saving his skin by literally shucking and jiving his way through a Dixieland song is just kind of a dated Broadway joke; a black Finch doing the same is DANGEROUS.