Calcutta University is far better than North Bengal University for studying law.
Although you can excel in your academics from any university, choosing a better one will provide you with more exposure. So, if you are interested in pursuing a degree in Law, I will suggest that you choose CU.
Yes, it is possible to score above 70% at North Bengal University. I have known people from the university who have scored above 70% and even 80% in their subjects. But it also depends on your subject. If it’s a science subject like Physics, Mathematics, or Computer Science that's achievable. But it’s a little tough for Arts subjects.
Also, recently NBU started a semester pattern and study. In the semester system, the question pattern was updated and it makes scoring above 80% easy.
Here is how you can collect your transcripts from North Bengal University.
Your transcripts may take 30 days to get ready. You will have to do follow-up calls to know whether it’s ready or not. You can visit the university to collect your transcripts or get them by courier.
Also, you should know that irrespective of which university you are taking, you will have to study on your own. You may get assistance from your professor or your friends. However, you will have to put in the extra effort to do well in your academics and get a job.