this is funny to me.. my Oscars best friend.. is a koi... the kois fins to get abit rustled up from time to time.. but my albino O prefers his Koi buddy to his other Oscar buddy.. I also keep an eclipse/sun cat with my Oscars and they all play nice. the cat eats any extra food the Oscars miss in their messy eating. I'de rather clean up more fish poop then rotting food scraps >.< icky! ... sounds like you've done some good research. If you're worried about cons breeding like mad.. just get one. They usually make nice dither fish.
Most Oscars will talk the talk but don't walk to walk.. w/ other cichlids.. so while your O may appear very aggresive.. be wary of overly aggresive other cichlids. I've seen Oscars that "bully" their tank-mates.. until the other cichlid/s have enough and just rip them apart. I'de start w/ some of the less aggresive species.. and build from there.
Also make sure to keep the 29 running once you set-up the new tank to QT any new fish that you intend to keep w/ your Oscar or as a "sick-Tank" incase you do have aggression issues. Or thats my advise. Don't forget to cycle your new tank.. so may be a month or 2 before you get the tank.. but you'll need ideally minimum another 1-2 weeks to get the cycle process going well.