You are right in the ballpark as to the year of that mower. In 1980, I purchased that same mower except it was the USA version. I still have it and it still runs great. In my opinion, you have what is perhaps the best Lawn Boy ever made. It is the perfect size for the average lot and my experience with the F motor is that it is long lasting and easily serviced. Yours looks to be in great condition. From what I see in your photos, your Dad took great care of it. Thanks for posting.