awww......now your getting picky!!!! I would prefer a 400 but I live an apt and 80 already pushed my wife's limit. If the tang gets to FULL GROWN and overgrows my tank then I will sell it and go back towards a smaller one.
I think the rockscape, minimalist!, will proove to be very helpful to the amount of swimming space for him. The end volume of tank+sump will be just about 100~ so I think that will help overall!