JMO,but think if you want the O to be a large,healthy,centerpiece of the tank then you need to look at dedicating more volume to it specifically.
The O and a single catfish (some type bigger than Pictus) plus 3-5 dithers (depending on species) would make for an attractive,active tank.
If open to suggestions,I'd offer up...

Ornate Pim (Pimelodus ornatus) for a catfish...and...

Spotted SD (Meytinnis maculatus),3 for dithers to go with your O.