Welcome to the forum.
To my knowledge there aren't any known or advertised factory barrels left that are readily available but who knows what might pop up on this forum, GB, or ebay, etc. There were some more recent manufacture Brazil (Imbel???) barrels that were available but I haven't seem one of those in a while but I'm sure they're out there somewhere and will likely be cheaper and more available than an original S&W. I was fortunate in that I ran across a NOS commercial barrel sometime ago to replace a shot out military one. From a financial standpoint, you'd likely be better off to find an original gun in the condition you want and buy it. IMO, what you'll have when you done with your project will be an expensive rebuilt non-original 1917. Which there's nothing wrong with that but unless you do the work yourself, you'll likely have more in it than it's worth. Just my opinion. Good luck.
ETA:
Does your chopped 1917 shoot ok now? Sounds like a dandy to me, post pics if you don't mind. I have several chopped 1917's as well as others here do too. We kinda like them.