Hey Old Coot, Yep, if it weren't a Sharps, that is what would have been first on the list. If you own a sharps, look at the barrel next to the receiver. If it does not have a tulip but has a Hartford collar, you can set it back but if the rear barrel flairs into the tulip, the forearm is not set up for it, you have a large hole. The wood and barrel aren't a match anymore.
Ted, I have regretted almost every firearm I have ever sold! Just hold on to that rifle. There is a gentleman on here, John Taylor and (his place is in the North West, maybe close enough to you to drive) he relines barrels. I hear he is good and reliable. The cost may be about half the price of a new one. Those large cases you have for the 45-120 bring a good price even used. I don't know how many you have. They could offset a little of the Smithing cost and take some of the sting out of it.