Howdy,
I have a pair of 2nd. Gen. Colt 1860 w/roll engraved cylinders that I use for mainmatch.
They are "U.S. Cavalry Commemorative's", and made in 1979 as far as I can determine.
I also have an Uberti 1860 Fluted Cylinder Army with a "CL" date code, so made in 2013.
Today I tried the fluted cylinder in both of the 2nd. Gen.'s.
While it seemed to fit both cylinder arbors nicely, and the overall length of the three cylinders were a near exact match, it would not unlock or index.
So there is evidently a minor difference in timing between the 2nd. Gen.'s and the Uberti.
If You are prepared to tinker with the timing Yourself, or pay someone to do it, it can be made to work.
But at least in my case it was not at straight forward swap.
YMMV.
(Personally I would use this as an excuse to order a brand, spanking new Fluted Cylinder Uberti. Or better make it a pair: It looks better with one on each hip, and it keeps Your back from going all crooked...!)