Acei aren't very aggressive and one of the few African cichlids that will occasionally school. I kept 3 Yellow Tail Acei' s together with no problems. Yellow Labs are comparable to Firemouths regarding aggression. More bark than bite. Males will beat on each other if not enough females are added.
As long as you hardscape smartly, I doubt you are going to have many problems.
My daughter bought me 2 male German Red Pecocks and one blue Zebra type Mbuna for Father's Day. That one is truely evil. The problem is I keep mostly CA Cichlids and Tetras. I guess I'll have my own 120 gallon African / New World, mixed tank.
Pictured is one of my new Peacocks, with his Texas Cichlid & Firemouth tankmates.
The second pic is the type of hardscape you might consider. It's of my 120 gal. A couple of years ago. All rocks came from my local rock yard, very inexpensive.