Of all my guns, only 1 or 2 like 3f more than 2f, and those shoot great with 2f. I much prefer it for open top guns just because it is putting up only 2/3 to 3/4 the pressure that 3f does. According to Keith, 3F was used for .31 and smaller revolvers.
Personally, even though the repro's are made of much better steel, I would feel a little queezy shooting 3f in Walkers and Dragoons. I have done so in the past, but I know more now than I did then. I have never heard of a new one being damaged by regular BP, but that is an awful lot of powder to be pounding on those barrel wedges. I don't have a Walker any more, but I do have a pair of Uberti 2nd Model Dragoons. They shoot well with a full service charge of 2F, a felt wad, and a .457" ball.
As mentioned above, you will also want to play with ramming pressure. 3F seems to shoot best right after you feel the "crunch" of the ball seating on the powder. 2F seems to like a good bit more, tho not as much as you are supposed to use for Pyro. Pyro likes all you can do short of bending the rammer. I have not fired one grain of Pyro in 30 years, and have no intention of ever doing so again. I would rather climb the learning curve of making my own BP than deal with that stuff.