Which of the various 40-70 chamberings is it? If it's a real Winchester barrel, it's rare enough. Sure would have liked to see it before the smith took his hand to it, no matter how good he was.
I had one in .40-82, but it wasn't very pretty and it's barrel was crap. Let it go, 'cause I was young and dumb. Now, I have an '86 in that caliber, and it's not too good either. Just my way of trading downward, I suppose.