I've never kept this fish personally, but although they CAN grow to 8" in size, i'd like to say would apply more for wild caughts.
Most other sites which show up in a search done on this mbuna say 4-5" and up to 6" in a home aquarium. which is a big difference.
However, I agree your tank is still to small for Adults. But if your upgrading anyway and can get some fry to start with, go for it.
I'd suggest pretty much other mbuna, even the odd hap, perhaps something blue to contrast with the yellowish, and of course the purple/ yellow ps. acei "msuli" is a great addition to any african tank.
Although your selected seems to be noted as aggressive, it is not hard to obtain harmony in a mixed community "mbuna" tank.
Cynotilapia afra 'Cobue'
Pseudotropheus acei 'Msuli Point'
Aulunocara stuartgranti 'chipoka'