Thanks for the links, Scott! I just found another article that suggests it's a basking shark, too.
Yeah, Quint's monologue is one of my favorite all-time scenes, and probably the best of the whole movie, too. I like how the whole evening scene about the Orca builds, with Hooper and Quint bonding over their scars and shark stories, and how Brody looks at his own appendix scar but then thinks better of it, and then Hooper triggers the story. It's put together so well.
"Anyway, we delivered the bomb."