Welcome aboard. Lake Malawi and Tanganyika cichlids like ph of 8 or above and kh of 240 and gh of 300 or higher. The coral skeletons will help but I'd use argonite for a substrate also. Your on the right path as far as cleaning the dead coral. Maybe bleach a few more time until the smell is gone and soak in some freshwater with Prime to neutralize the chlorine.