No idea what the right section for this is, but find a Deep Blue dealer and you can get the 57 gallon (same dimensions of a 40b, just taller) for at or under $300 (depending on their markup).
It's a gorgeous tank. Not the best by any means, but certainly built above and beyond a standard 40b. Super thick glass, so think it might be intimidating to drill. But it is drill-able and I'd recommend that as the "Reef Ready" version has a ridiculously huge overflow that takes up way too much real estate. I have one on order and am going to put my Modular Marine overflow on it, at least I hope to. Mine was made for way thinner glass, so I'll be doing some measurements or contacting Modular Marine to make an adapter.