Well, folks, it seems I made a miscalculation. This tank will be for the study in a new house. I've done some remeasuring, and I've actually been shorting myself on tank size. A 6ft tank is easily doable in the space.
I'm now targeting a 150 gallon (72x24). I'd still like to stick with a severum as the big centerpiece. Is my original wish list more appropriate for a tank this size (severum, EBA, 4-5 Geos, 12+ Columbian tetras)? Any other colorful, relatively peaceful options I should consider (maybe a flagtail)? Bearing in mind, I don't want to get too complicated in terms of feeding.