I'm going to have to agree with Dave here, I don't quite think you got what he said though. What Dave is saying not only is the minimum tank length for a coral cat 4ft long but also 4ft wide and 4ft high and 6x6x6ft for a bamboo to allow for enough swimming and turning room for the shark. You also need to be aware of and be capable of handling the exceptionally high nutrient and bio-load that sharks have, they're messy predators so they require serious feeding and a properly balanced diet!
Personally I would be having a thorough discussion with your marine biologist buddies and also both aquriums before you even set the tank up so that you know, 110%, certain that they would be happy to take the sharks and care for them and what they recommend about doing with sharks. I know I wouldn't be getting one unless I'd spoken at length about everything including contingencies, sharks can be fragile creatures and need to be treated with a lot of respect. Now I'm not saying that you aren't capable of all of this or anything like that and I'm sure that you could quite capably raise some sharks but I also tend to feel that it sounds like you might be a little under prepared here, I think that's why Dave said what he did because I'm guessing he's thinking the same way.
Sharks like Moorish Idols and a lot of Butterflyfish are rather abused and not taken care of properly due to people having no idea what they're actually buying into. I'm sure you've done your research and could be prepared for this but things that tend to suggest otherwise (which you can prove wrong
) are the fact that both sharks have 300 gallon plus tank requirements and you're offering half that, you don't have a lot of info on your plans for the tank, at least in your post and like I'm sure is the case with Dave (please feel free to jump in if I've made any incorrect assumptions here Dave
lol) I'm also worried for these animals not because of you as an reef keeper but due to the mistreatment that sharks get. I'm really not having a go here, I'm just trying to help out and getting some more info from you about your plans and all of those kind of details would help put me at ease immensely
If I've come across as offensive I am terribly sorry but at the same time sometimes things like this have to be done bluntly.
I'd love to hear your plans further though, sharks are incredible creatures