To start with, you need to know where he was in 1860 and what his dob is. We know he was in Arkansas in 1880, but where was he before that?

If I had to guess, I'd start with the ones from Mississippi.

Was Michael his first name or his middle name? Could he have been Archibald M. McIntyre who lived in Alabama and served with the 6th AL Inf and then, after the war, used his middle name? Could he have been J.M. McIntyre and ridden with the 4th Mississippi Cavalry?

I think you need to do some more talking with family as to who he was, when he was born, when he lived and where.

JR