hello Ar,

your chance with the 70k OBC rank is less. if your general rank is about to 80-90k then you can surely get a seat in Nirma University.

you can check here the cut off of Niram University here and cut off of all branches-

https://engineering.careers360.com/articles/nirma-university-btech-admissions

hope it's helpful for you.

Good Luck.