i wouldnt do it for a variety of reasons.
1. tank is much too small.
2. water parameters are like night and day.
3. diet is completely different.
4. a fish that size will eat your smaller mbuna.
i dont want to come across like a dick, its just that imo theyre not compatible, especially in a 75g tank.
im not a mixed tank guy, i dont even like mixing mbuna with peacocks and haps.
in the end its up to you, but i dont think it would be a good decision.