I think you will be fine keeping cons and rams together, keep in mind that the water parameters should be centered around the rams needs as they are a more delicate fish. And the cons I kept weren't terribly aggresive, I think they are one of the more docile cichlids out there. But some people have put them in their "Top ten aggressive cichlid" list so YMMV
umm, okay Thanks for your responses, maybe it depends on the personality of the individual fish. I just don't want a barren 50 gallon fish tank but I don't want a bloody massacre either.