The gun you are looking at is the model 544 which is the Texas Wagon Train Commerative, chambered, as you said in .44/40 Winchester. It is an N-frame with a 5" heavy barrel. These guns were made in blue finish only, with gold inlay in the lettering. I am unaware that they made any in nickel, though the 1 of 10 marking leaves me intrigued. The one you are looking at has been refinished if it is nickel. It's value is only as a shooter as it's collector value has been destroyed. $650 is way out of line for a refinished gun! I'd say it's value is about half that as a shooter only. I would pass on it, as I do not buy refinished guns that someone has messed with. Who knows what else has been done to it? There are plenty of clean, original condition Smiths out there.