> Can a large amount of text be put into a quizport question field,
> or should I be looking at a different module?
QuizPort expects the content and questions to be in files, not fields. The files may be static html files, or they may be interactive quiz files, e.g. Hot Potatoes quizzes.
Looked at this way, you question becomes, "Can a large amount of text be put into a file", to which the answer is "Yes".
However, of course you need to bear in mind how much you think the students can digest in one page at a time, when they access the information using their favorite browser on their favorite viewing device.