I have a featherfin cat in my mbuna tank and they do fine together. They don't even notice each other.
Also, I've noticed in my tanks that if you combine fish that tend to occupy different areas of the tank the aggression is greatly reduced, or that look completely different.
So with the labs, most peaceful bottom dwellers would probably be okay. Also I have a school of tiger barbs in one of my tanks with OB peacocks. They pay them no attention whatsoever. I've also had a few gourami in this tank at one time. Nobody paid attention to them either. I guess they just don't see them as competition.
I know some people will adamantly tell you not to do this, and I am by no means an "expert", but in my tank it works. Hope this helps.