Coral beauty and the long nose might pic at inverts...but are usually classified as "Reef-Safe". I would do this without being too worried about anything funky happening.
Stock away, or come back with a more specific question so we can help you more.
Most online fish stores will tell you what size aquarium the fish you are interested in need. You can do a lot with 300g...depending on the footprint. Height above 2' is pretty much wasting space in my mind.