I think you need to work from the point this Spencer enters your family (I assume that he enters your family at some point and that's why you're interested in him? If not, then why are you interested in him?).
Where did you get the information you listed? If there's no document, then someone must have told you these things. Is that person still around to tell you something more? Are you sure that what this person told you is correct -- was true in the first place and was remembered correctly?
What else do you know about your Spencer? You say he was a widower in 1977, which I assume is the date of some specific event -- a marriage, maybe? If so, who did he marry? Can you find a record of this marriage? If not a marriage, what happened in 1977 to cause someone to remember anything about him (and these specific details in particular) and pass this on to you?
Where did he live? Where was the unknown event of 1977? Is there anyone still around who might remember the event?
As I said, I don't really know where to look beyond what I have suggested. And I can't think of any way to confirm that Spencer C Peterson is the Spencer you are looking for without knowing more about your mystery Spencer.