Beautiful tank!!!
Chances are you won't be able to keep multiple aggressive Acanthurus tangs long term in your tank. I know they are fairly common(atleast over here), but if you want a school of tangs, look at yellow tangs, Zebrasoma flavescens, with an odd ball mixed in here and there(Atlantic blues, Acanthurus coeruleus, and Bristletooths, Ctenochaetus sp., school well with yellows and would provide good contrast) and then an Achilles or Powder Blue.
BTW, how did you ever catch that Sohal out of there. A fish trap or hook and line? Amazing feat in its self!