Yes, black Republicans in the South were the champions of civil rights. So were northern liberal Democrats. Southern conservative Democrats (Dixiecrats) AND southern conservative Republicans were bitterly opposed to Civil Rights. In fact, southern Republicans actually voted against it at a larger percentage than southern Democrats: http://en.wikipedia.org/wiki/Civil_Rights_Act_of_1964#By_party_and_region
And again, as soon as it passed, the Democrats lost the south. It was the one thing that southern conservative racists hated more than Lincoln's Republican Party, which is why southern conservative racists are Republican now.