] Would James actually be a GREAT catch for her?

Actually...yes, I believe he would. Aside from his personal attributes that might teach her some manners (though not likely), I think that a future clergyman would be a great catch for a woman of very little fortune.

Isabella, though beautiful and not destitute, isn't very wealthy, either. No man of large fortune is likely to take her on the merit of the match. Maybe that's why she spends so much time "working it."