Marriage

Given facts indicate that the marraige is illegal as your name indicates you are Hindu.

Sapinda relatioship is counted only through patriarchial heirarchy except with regard to one's own mother. Prohibition for marriage between cousins is up to 5 generations on the father's side and 3 generations on the mother's side, counting the person himseff/herself as generation 1. You are cousin of the father of the girl beyond 3 generations on his mother's side. And you are marrying his daughter only. Go ahead you can marry her.