I never once said I had anything against black people.
Of course God calls men of all races to His Priesthood.
I am philosophically against the destruction of all races into a single mongrel race, where race basically disappears. I believe that God willed that things like countries, cultures, languages, and races come into existence, and stay in existence. If God's plan was to have just one race, we wouldn't be having this conversation.
FYI, it's the Jєωs (the world's biggest racists, by the way) who want all of us GOYIM to blend together into one mongrel race, with no countries or borders -- all living under Jєωιѕн tyranny. Sound fun? I didn't think so either.
I think that, all things being equal, it's better for a man to marry within his own nation. It's also better to marry within your own socio-economic group. Even Scripture talks about how foolish it is for the rich and the poor to try to be friends. For the sake of martial harmony, it's best if each spouse comes from a similar background. Views about money, child raising, discipline, lifestyle, etc. can become huge issues if there is a great disparity between the spouses. Marriage is difficult enough without starting off with a huge handicap!
I think it's common sense that each should try to marry one of "his own". Look at all the identity issues faced by those of mixed heritage.
The best chance of happiness for a mixed-race couple is if both of them are Catholic. But even then, there might be plenty of earthly struggle in store, if their families were very different. Culture is an important factor in defining who we are. Generally speaking, culture, nationality, and race are related.
Each nation or people has their own strengths and weaknesses, and role to play in this world. It doesn't really matter who is better at what in this world, since our common goal is the growth of charity in our souls, to attain to a closer union with God and a higher place in Heaven. That can be done by men of good will OF ALL RACES. I'm sure the struggle against sin and self will take different forms depending on your natural virtues and temperament -- but everyone has to fight in this world to prove they love God.