Cj, here is the stocking recommendation for your 55 g Mbuna - 3 each of the following fish you have chosen:
Saulosi - will be the most aggressive
Rainbow Cichlid (Central American Cichlid) - may get picked on, maybe not but I don't blame you for liking these fish, very pretty color!
Give me a call or shoot me an email if you need anything, I may not be on the forum much - Best wishes on your new tank, it will be awesome I am sure!!