I had 3 pairs in a 90 gallon tank with 2 Oscars and had no problems . BUT when the Oscars starting to get brave and see what was in the pots that the convicts were using they liked the taste of the new fry . Thats the problem I think your going to have with any tank mates.
I have a 55 with about 10 Black Convict Cichlids (5 of them first generation and the rest second generation). I threw a common pleco in there to do the house work and he's doing fine.
I have read countless forum posts stating that nothing will make it in the tank if the Cons start breeding. I have a breeding pair that tried once with a few survivors (the 2nd gens), but since then, nothing.
Is there a hearty, robust cichlid (or two) that could make it in the tank to give me a little more variety and personality?