those damsels alone will cause problems. ther is a high possibility that they will nip at the new tang [especialy if its small], and eventually kill it. if your damsels are nicer then mine, your tang wil need a biger home in about 6 months max, no matter ho small you get him. they tend to like to swim even when they are small. clownfisah might have same problems with damsels.
good luck.
i think you should first upgrade and then consider hippo tang cuz they are like ich magnes, and moving it from tank to tank will cause more stress [ich]
good luck with whatever you decide.