HI there,

First of all congratulations on scoring such good marks in the written exam
and you got 100 marks in the SSB part which is a little below average but Ok since the cutoffs are calculated on the basis of written and Cumulative marks.
Now, the cutoff of NDA is released on the basis of your marks and how your fare in the medical examination.
For the cutoff, according to the previous trends the overall cutoff is around 670-680, hence I would say that it would be tough luck for you to get into merit list but you have some decent chances.
But before that, you must have to clear the medical examination without any permanent rejection.
Good luck to you buddy.