No apologies needed my friend. My reply was meant as a suggestion that the search continues, not that one answer is correct.No problem. It is a thoughtful gift idea you have for your father.
Sorry for posting a Google result, it seems like Google sometimes has different results here in Europe but maybe not.
Your reasoning for Dr. Grabow sounds good.
I will say that this has been a fun rabbit hole. I have learned much about the classic American pipes by researching this in more depth. For example, I better understand why @crashthegrey enjoys chasing the Kaywoodie pipes and there are also wonderful collections of 1940-1960s American pipes out there. I am now seriously considering getting a few older pipes to add to the collection now.