I am serious about the purple they relatively small, relatively nice and hardy.
As far as the regal goes, I don't want to sound like the tang police here, but you are already planning to pack a lot of fish into a 90. If I hadn't seen your tanks in the past, I might question that choice.
Regals are really hard to get in healthy. Even then they are very shy. Mine were always the alpha fish in the tank. You have a pretty tough and outgoing neighborhood planned. I think you will have a really hard time getting one to settle down in that environment.