Colt has been making left hand barrels since the start, I guess - my early and mid 20th century revolvers are lefties as is my 1980s Officer's .45ACP. So is my 1884 Lightning rifle. It would be no surprise to me if the 2nd and 3rd gens were the same.
As for the reproductions, Pietta's and Uberti's C&B Colts are left twist. Pietta's Remington is also a lefty, at least according to Midway (alas, the powers that be will not allow my gun collection at work, so I can't look to be sure).
Oh, and according to
this post on Colt Forum, Colt always used progressive twist rifling.