I'm not a shark/ray keeper, and your tank has a nice footprint, but even so, you'd be looking at one of the smallest elastomobranchs, and nothing that swims. However, I think the tank would be pretty tight. Again, I'll let one of the shark weenies chime in.
As far as other cool fish, large or medium-bodied lionfish would be really great in a tank like that, as would larger scorps and stingfish (Inimicus sp). You could fill it out with an eel (such as a zebra), squirrel/soldierfish, a Xanthichthys sp. triggerfish (a male blue jaw would be great), a marine betta, etc.
Here's a link to a good lionfish article with lots of nice photos of the various species:
LIONFISH CARE GUIDE
FWIW, we have a 210 gal build we're doing that will house four medium-bodied lionfish, an Inimicus stingfish, and an Aussie harlequin tuskfish for starters. We already have the fish in various grow-out tanks as we tend to get our fish on the small side as we like to grow them up.