I have a Haplochromis moori and a Nimbochromis venustus in my Mbuna tank and they spend their time swimming together in a pattern from surface to about half way down and swimming in the flow, although they go to the bottom to sift sand sometimes they spend most of their time in open water. I also have a Nimbochromis livingstonii which I can't say enough for, he is wonderful. Only a juvenille but loves to play dead in the sand by the rocks where the baby Red Top Afra hide trying to snag himself a snack, brilliant fish.
Can I just say also that if the reason you want a top dwelling fish in a Cichlid tank is to get more activity throughout the tank that a bit of increase in rock height may promote a greater spread. Many of the tanks I see on Youtube are only filled with rock to only a third or less up the tank, and the mbuna are unhappy to stray too far from them. If you fill the rocks to higher up then the activity will move. In my tank its high rock either end and low rock thorugh the middle and the rock dwellers definately like to stick to rock level, but are happy to play near the surface by the high rocks.