Well I think Bob Fenner is the end all be all of proper fish care(funny you dont even mention him) and this is what he says:
The Common Porcupine Puffers (Diodon holacanthus)
This is a very wide spread species of puffer, found in almost every major warm water ocean, Pacific, Indian, and the Atlantic Ocean. This is a member of the Diodontidae family, which also includes Burrfish. The separation between the Diodons and the Tetradons comes from the armored and spiny bodies of the Porcupine and Burrfish.
This is possibly one of the best puffers you can get for your tank. Providing that you are going to be getting a tank that is over 100 gallons.
Also, to clarify a 75 might be fine for a full grown puffer in a tank all by itself with almost no live rock. Once you start considering additional tankmates and space taken up by live rock though a 75 is awfully cramped for a foot long or more puffer.