This all depends on the size of the tang. They get big and have a tendency to be aggressive! Your tank is on the smaller size for that tang. I would recommend no less than 200 gal and preferably more. Or, make sure you have a person with a larger tank ready to adopt him when he outgrows your system. I have a Dussumieri in my 125g. She is ready to be released back to the wild in just over two years and, really, should have released her sooner. My 2c.
You will be storing up problems. It isn't necessarily your current stock that will suffer, once it settles you may not be able to add any new fish without them being (at best) bullied or (at worse) killed.