yes they should be fine cause i had the same fish in my 55g and they were fine together just make sure u make some hiding spots just incase they dont work together
It depends on the Jack Dempsey. I had one that was a community fish and not very agressive at all. But there are some that are extremely agressive. Your best chances are to raise them all together insteal of buying full grown fish.
I'm keeping Jewels, Salvinis, a Dempsey and a Firemouth together. The Salvinis are receiving most of the abuse in the tank...especially from the firemouth...he is one nasty little fish. I'm thinking of returning him to my LFS.