I had one in a 65 gallon for a while. It was fine until I went on vacation to Europe for 3 weeks, and someone overfed it. All the fish ended up dying right after I got back.
They reach 5'. Ideally, I would think at least 300 gallons (guess) for him to reach full size. The most important factor though, would be your set-up and water change routine. How about lots of live rock?