This is a pretty good chart-pic-thing to compare the typical styles from some of the more "famous" toony makers:
http://www.furaffinity.net/view/15336245/ (Or well, most of Syber's gallery is probably a good place to look and compare, what with her owning a small personal army of Syber-suits. That pic just makes it easier to to tell who made which suit.)
Another maker who make nice toony suits (but seem to have a wider range of styles/creatures built) is Beastcub.
Moving jaws (as in more or less properly articulated ones that moves when you talk) tend to not work too well on toony suits, but it all tends to depend on the head-shape of the suit and the shape of your own head.
As for the eyes, I personally think toony suits look best with toony buckram follow-me eyes. Those also tend to be the ones with the best vision.
The only other "optional" thing I can think of are digitigrade legs, but seeing as it's supposed to be a shark-suit, I guess those can be left out.
As for reference sheets, keep in mind that fursuit reference sheets are best left clear and "simple". Many makers have "official"/recommended reference artists listed on their business pages, so those are good places to start looking.
Those artists are probably the best ones to approach for something like this too.
