The seat loooks like something he would have picked up while in Mexico. They were stock on Windsor’s in the 70’s . I have a 1972 Windsor Pro with matching jersey and the jersey is labeled with Lambertini. If you want to get rid of that seat I may be interested. I have never heard of this brand , but appears to be mid to late seventies or late. The Japanese bikes were very nice in those days , yours looks to be in nice shape.