With those inhabitants I'm sure the tank is large enough, my volitan currently has a picasso and majestic angel as roommates, as well as a yellow belly dogface puffer. I've had an assortment of tangs, angels, puffers and triggers with my volitans in a few tanks over 30 years, and never had an issue. I've had a golden puffer with a volitan in one of my tanks years ago, no issues. My current tank is a 210 and my volitan is a solid 12plus". The fish know how to stay out of his way and unless threatened would general not attack. The line up you have would be fine with a volitan.
I'd be more concerned with the addition of the eel, both the eels you are interested in are fang tooth eels, and they do have the capability of taking down any of your fish. These eels have been kept successfully in community tanks, you just have to be careful. Try and get a medium to one on the smaller side, a large mature eel direct from the ocean will cause more concern. Keep them in an observation tank to get them eating dead food, I would do a couple of months. I've seen a dragon eel take down a show size blue tang, although for the most part these are friendly eels, for a fang tooth eel that is.
