USMC brings up a good point. In my 8-feet 300, I have a yellow tang, a Sailfin (desjardins), a Purple and a blue spot bristletoogh. The blue spot is the only one I bought from an LFS. The yellow was a freebie from a tank tear down. The purple was a trade (I basically stole this one) because he had outgrown his tank and the Sailfin was a "quasi rescue". A friend was selling his livestock as a result of a tank tear down. He was very picky about the tangs going to larger tanks (from a 185), not smaller.
In my other tank, I have a purple and a sailfin. Both from a tank tear down and the owners desire for them to go to larger tanks (from a 220).
Main point......what is the maximum adult size the fish will get and are you able to provide them with a proper home when they get to that size?