Except that both of those species are highly conspecific aggressive and require 12+ just to have it sort of work. I've heard of very little success keeping either species in a tank under 4'.
I'd look into some of the Tanganyikan shell dwelling species such as neolamprologus multifasciatus, brevis, or ocellatus. Other than those, there aren't many species of African rift lake cichlids that will do well in a 30 gallon. Generally the rule of thumb for mbuna is a 4' tank of 40 gallons or higher (40 long is a 4', 55 is the most standard 4'), peacocks I personally say a 75 gallon or larger, and haps I would say a 125 for a proper tank. These are all my personal opinion.
