Hopefully he will give you the right answer. The only reason I say that is I tried to buy a C that was suppose to belong to my father, come to find out, these two guys got together to try to con me out of my money and to get the tractor out of one of their yards. This is a little redundant, and just my two cents, but I believe that if you don't buy that tractor, you may regret it for a long time. I have not been blessed with the history of my family in the form of an object like this, but I would buy it if I had the chance. As the others have said, sell one that has no sentimental value for you if you have to, but get it if you can.
Life is funny.
Got it after it had set for years with a stuck motor. As a young boy I used to set on the seat and think about how I would wheel that M around. Now some times I set on the seat and think about Dads big hands on that wheel. You know what the right thing to do is. First off, Congrats on the little one.