Yeah, being black is the only real "twist" Marvel added to the Blade character. If you change it, you just have one of many fictional "half-breed vampire hunter" types.
You could make BA Barracus white, I think. What people associate with the character is the idea that he looks tough and is very strong, but acts endearingly silly and childish in some ways. He's from the same basic archetype as, say, the Thing.
So, let's say you dress BA Barracus up as more of a Hell's Angel biker than an inner city street tough. He can still have the mohawk and be covered in tattoos and chains. If he still drinks milk and won't fly in a plane and loves his van, that's BA Barracus.