I would defer to those with books and experience regarding the Paris markings but to me this seems like a later 19th century cavalry officer sword for the French market.
There is really no such designation as an American 1860 cavalry sword, it was simply addressed by the ordnance paperwork as the light vs heavy. You realize that the basis of these does go back to the trooper and officer cavalry swords based on the French 1822 patterns. The smoothed many branched guards actually go back to the 1816 patterns, when we see the branches not ending in an earlier balled form.
When looking at the American market and derivatives, we see the light sword adopting what was basically the officer version of the French mle1822 form. The slightly humped grip and lighter blade showing in the trend from the trooper to officer swords and then widely adopted during the American Civil War as the defacto (although misrepresented) 1860 pattern. There were both heavy and light officer versions made by Ames and as far as the trooper swords, there is overlap of both grip and blade combinations with the first plain "light" trooper builds appearing by 1857-1858. Complicate that further with what was produced in Solingen and the American market swords show quite a diversity, with some quite normal looking 1822/1840 trooper swords being the bulk of the American heavy designation.
Without absolute provenance of sale to an American during any given war period, the attribution as a civil war trophy is spurious at best. I have a completely unmarked trooper ("wristbreaker") that has a better basis as possibly imported for use during the ACW but I simply look at mine as "in the form of" and a nice example.
You sword looks quite nice and should have every reason to appreciate it for what it is but more or less completely remove from thought that it had anything at all to do with the ACW. The guard on yours looks almost like an evolution to the "new and improved" hilt of the French 1890s cavalry swords. You may enjoy the following link if you have not browsed through it yet.
http://users.skynet.be/euro-swords/
the following section particularly
http://users.skynet.be/euro-swords/M1896OC.htm
Did you get a scabbard with this? Single or two rings? As mentioned, this looks like a nice one. I have seen horn grips as late as the twentieth century with very much the same overall profile for these swords.
Cheers
GC