The Wrong Longs?

The discovery of my great-grandfather's death certificate has raised a number of issues, the first of which is that I may have been researching the wrong family as my great-grandfather's parents and siblings. How could that happen? Easy. Just watch this. My great-grandfather's name was James William Long. I assumed for my initial research purposes that he was born in Kansas City, Missouri. I assumed that because credible witnesses told me that he had lived in KCMO "all of his life." My grandmother, his daughter Annie Florida Corrine Long, was born in Kansas City and left there only twice (to come visit her daughter, my mother). This assumption was furthered by the enumeration of James Long in the 1900 census, which gives his birthplace as "Missouri." [How do I know that this is the right James Long? Well, his wife is stated to be "Mary E." and I can verify from other primary sources--like the marriage license itself--that James W. Long and Mary E. Johnson of approximately the same ages were married in Kansas City, Missouri, in 1888. The children listed are also verifiable from other sources]. My James Long doesn't seem to be on the 1880 census. But, ah, here on the 1870 census for Kansas City, is a James Long of the right age, 4 years old. He lives with his parents, James and Nancy. Now that mother's name doesn't seem to fit some other research, but, oh well, first names and middle names are frequently interchanged in census records. His siblings are Charlie, Fred, Hannah, and Rebecca. My Aunt Delorise (my mother's younger sister) had told me that she didn't know her grandfather's father's name. She had heard him referred to as "Old Man." She thought his mother's name was "Pauline," or something like that. She wasn't sure. And she wasn't sure of his siblings' names. So the James Long on the 1870 census--the only one who matches what I'm looking for in KCMO--must be the one I'm looking for. Right? Well, James William Long's death certificate says he was born in Shawnee, Kansas. The informant is his daughter, Christina Long Neal, a generation older than Delorise. So let's look at the 1870 census for Shawnee, Kansas. And there is a James Long of the right age, 4 years old. His parents apparently are Richard and Palinay (Pauline?) Long. His apparent siblings are Joseph, John, Regetha, and Eliza. But wait a sec, this says he was born in Missouri! So which Long family should I be researching? As I once said here, paraphrasing my former neurologist, "There are no easy cases in genealogy."