Ah yes... You're referring to the mini series "The Truth: Red, White and Black", and that happened in the mainstream Marvel Universe (Earth 616 as the Watchers call it). Although, that would not work for the movie... It's very "Flowers for Algernon". The Weapon Plus program has long been known to experiment on minorities, people the general public wouldn't care about. They would start experimenting with Mutants during the Weapon X program. But with Weapon I, they were experimenting with a different type of minority, African-American soldiers. They had the Super Soldier Serum, but it had yet to be perfected. Most of the soldiers died or were hideously disfigured, But it worked for one of the soldiers: Isaiah Bradley. He went on one mission as Captain America, but eventually he lost his cognitive abilities making him somewhat of a slow witted hulk of a man. With the data they recorded from that program, Weapon I would develop the serum that would eventually be used on Steve Rogers, the man we all know as Captain America. Isaiah's grandson, Elijah would inherit his shield and currently fights crime as a sort of teenage Cap, The Patriot. I'd love to see it as a movie, but Hollywood doesn't have the balls, and Will Smith churns my stomach even as a choice for Isaiah. I'd go with your earlier suggestion, Tyrese... that man is a mahogany god.
If we're going with a going with the Steve Rogers Cap, It's a tough call. I'd have to say Brad Pitt could probably get it right. His performance in Legends of the Fall captures that era and people's sensibilities (It was about 20 years earlier, but still early 20th century). Although with his current activist activities, I doubt he'd sign up to play "Captain America". But Will Smith man? COME ON. That's not even a situation like with Kingpin or Nick Fury where the actor that best suits the character happens to be black. Will Smith would try and crack too many "witty" Michael Bay action hero jokes like "here's shield in your eye" or some shit like that.
If they are bringing the mainstream Marvel portrayal of Cap he should be like your dad. He may be slightly square and not exactly "with it", but ultimately you respect the hell out of the man and will do anything he says. If they go with the "Ultimate" interpretation of Cap, he should be like every gnarly old WWII vet you've ever talked to, but still have the body that makes you believe that if you sass him, he will fuck you up. I like that version. He kinda reminds me of my uncle Tom. He was gay, in his mid 70's and only had one leg, but I still believed he could probably take my ass in a fight, hell the man stormed Normandy. Ultimate Cap's neighborhood from the 40's had since turned into a shithole ghetto while he was frozen, but he refused to move just because a few "bad elements" had moved in. He was late to an Avengers press confrence once because he was chasing down some punks that had broken into his apartment and poured acetone on his collection of 45's. Yeah, that's the Cap I wanna see.