Is there a mold seam on the edge of the scabbard? Is the date stamped on the blade? From your photos it does look like a cavalry saber, but there are a lot of repros floating around out there.
The sword is currently at my father's, I will check next time I see it. I don't believe there is a seam, but I will check. Don't remember any dates that I could find. Most of the markings were pretty worn if I remember correctly.
I work with an older guy who has 2 swords that belonged to 2 of his ancestors that fought in the civil war. 1 fought for the north and the other for the south. They both look very much like your sword so I would say yes it is. You can usually tell how much action they saw by the amount of damage on the blade.