Only a sadist would combine a spiny eel with cichlids as territorial as Jack Dempseys or Green Terrors! Don't do it!
The large spiny eels (e.g., M. armatus, M. favus, M. erythrotaenia) seem to do quite well with Oscars in large aquaria. As ever, your problem is feeding the spiny eel, so I'd get the eel settled and hand-feeding before adding anything competitive.
Macrognathus spp. are sociable (i.e., keep in groups!) and easily bullied, and are completely unsuitable to this kind of community.
Cheers, Neale
Hey from what you might think from the title this isnt a plee to help me choose oddball or new world, I just wondered if in a 5x2x2 or a 6x2x2 I could get a peacock eel, Jack dempsey and oscar or GT, maybe a few silver dollars, I didnt know where to post this and as I was going through oddball forums I decided to post it here because of the peacock eel..