With Moria's introduction and his obvious laziness, we have a little more to work on with this:
B. Kuma: Wrath (?)
Jimbei: Gluttony (?)
Unknown: Lust (?)
Kuma and Jimbei don't particularly strike me as the kind to be lustful. Doflamingo in his own right is very envious of dreaming pirates, Crocodile was very Greedy and went to extreme means to obtain an entire nation as his own; Moria is obviously very slothful, considering his personal motto and his constant sleeping; Mihawk is very arrogant and Prideful, whether he has the right to be or not. We haven't seen much of B. Kuma to make a judgement, but we do know he is a huge man who carries a bible. That's all. He doesn't particularly strike me as lustful, though.
Whale Sharks are filter feeders and eat a TON of food, so Gluttony makes a good guess for him.
Perhaps it's just coincidence, but who knows? I mean, put in the right context, it would make sense if the Shichibukai DID represent the 7 deadly sins. Part of finding One Piece could be the Absolution of Sin.