If you pick a CBB that is large and healthy enough to have survived shipping stress, and it does well for you, it will grow like a bugger. I don't know how many fish that size you want in your 75... Plus, you probably don't want to be putting any unnecessary stress on that beautiful Tang...
Personally, I would pick something smaller but equally personable and attractive. It's a tricky balance, I know - what about a dwarf Angel?