I don't know who told you two Oscars would not be a good idea, how do you think they breed
I have got three Juripari and they are just fantastic fish. They make incredibly compatible tank mates for Oscars, as long as they are not too small. They are very placid and don't have an aggressive bone in their body, apart from squabbling with each other occasionally but they never cause injury to each other.
You could have two Oscars with no problem. Maybe an Oscar and two or three Juripari, I must say that from my experience they really do like being in groups. Never had a Jack Dempsey before, there are semi-aggressive so you always run the risk that they could be a little bit bully-ish towards other fish. However, you could have an Oscar, JD and maybe a couple of Juripari if you've got some very good filtration. Apparently Juripari can reach something like 10 inches, mine are around 5 inches and I've had them for three years so unlike Oscars, you should not huge fish on your hands in a matter of months.
I'm sure someone else will give you the benefit of their advice