Unfortunately this is probably a bit too late, but it may help others with the same ordeal.
Definitely choose a class in which you did well, but don't choose it solely on that basis. Probably a professor from the department in which you majored, department head would be a good idea as well as long as he/she is someone with whom you've had at least one class. As for how to get ahold of a prof, I'd call student services (the people who do registration and the like, it's called student services at my U) and ask for email, office phone numbers and the like. Youi might try the school's web directory as well.