Bruce,
Although I make no claim to being an expert on weapons, I have been collecting Civil War & Indian Wars weapons for almost 40 years so know a little about them. In my estimation, the revolvers mentioned were not the figure 8 Savage as they and the Alsop were the models that the Savage/North was patterned & improved on. Approximately 11000 were bought by the Government. The Savage was a very cumbersome & complex weapon to handle & the weight of the pistol plus the complexity of having to cock the the bottom ring & then remember to fire the upper trigger was a wee bit much for most cavalrymen of that era. There have been reports of battlefield found Savages with all 6 chambers found loaded, all caps still intact with the hammer back, indicating that the trooper just kept cocking the revolver & forgetting to fire it. It is understandable how this could happen in the heat of the battle.
The reference to the French Dragoon revolver has me a little puzzled although the description certainly identifies the Savage to a T as it was heavy at the muzzle & I feel Leslie's reference is most likely correct.
I have seen a documented Savage offered for sale showing it was issued to a New York Cavalry regiment, recently. But that can be misleading as Regiments could have a mixture of different issued weapons as that was indicative when Springfield Research Service was still offered free, on line but has since taken it's service offline. That was a shame for those of us trying to make sense of what was issued to which Regiments but cannot blame the provider as unscrupulous people were making money off the free service. A real pity. A suggestion that may help you in researching the 2nd Colorado issued weapons is google Springfield Research Service, contact the provider & subscribe to his service which if I remember correctly was $25.00 @ year. If there are any hit's on Savage's issued to the 2nd, it would be on his list. The same list may help you on the search for the carbines also.
In closing, as a Missouri boy, I frequent the the Missouri Civil War board daily & thought of posting there also but posted on this site.
As a side note, I own a documented Remington .44 issued to a trooper of the 1st MO. cavalry that chased Guerrillas throughout MO. The documentation came from Springfield Research Service & from that info, I was able to document the trooper from birth to the grave. Quite fascinating.
Anyway, good luck on your quest.