Hi, Damien - and welcome!
I'm no tang expert, and not too sure of the liters/gallons conversion - I think you're at about 130 gallons or so?, but I'm told that it's easiest to keep tangs of different genera together. So hippo/yellow/kole ought to work well enough, but sailfin/powderblue/purple might be more difficult, due to both the sailfin and purple being members of the Zebrasoma genus. (The sailfins get pretty big all by themselves, something to keep in mind.)
I'm looking at stocking a 220 gallon tank, and already have a kole, (Ctenochaetus) so I'm giving some thought to adding a powderblue (Acanthurus) and maybe a purple (Zebrasoma). Keeping tangs of the same genus - even the same species - in a tank can certainly be done ... but may require some rather cautious introductions.
~Bruce