IMHO you'd be fine with either tank. Gulpers are a challenge and, I am not afraid to say, no one in the whole world has grown them to their full size except one case I've heard of, viz., a 14" gulper somewhere in Asia.
Mine lone survivor is 4 years old and is still around 9"-10".
They have proven very hard to keep alive and well long term for 999 people out of 1000, or worse.
They love a good swim at nights but they are clumsy swimmers, so no great space is needed. No great current is needed. They sometimes still swim rubbing a glass in a circle even though having a large tank, like my 240 gal 8x2x2. So, get one, observe it, make adjustments as needed, I'd say.