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.