When I wo4ked at the gun shop, I had many variations of this question asked me over the years, about both muzzleloaders and other antique guns. In general, especially if the gun looked like it had been dragged behind a mule with diarrhea for twenty miles and then put into a damp basement for a hundred years, I would advise them to clean it up, coat it with oil and hang it on the wall. Under no circumstances would I ever suggest that they shoot it.
Damascus/twist steel has it's own problems. Those welds might have been fine a hundred years ago when the barrel was new. But since then, the rust has had a century to weaken them and there is no reliable way to say when the barrel will fail.... catastrophically.
Before about 1920 or so, nobody knew much about making steel. Batches varied in characteristics. Engineers often compromised by over-engineering the part in question. Winchester Model '73s and their descendants were good examples of this. Take a look at an early Rolls-Royce frame if you want another example.
Years ago I had an old shotgun in the store that had been found in the mid-1950's out in a field wired up under the running board of a Model T Ford. Now, figure that gun was probably out there since the twenties. I'll leave it to the imagination as to what it looked like. A youngster bought it, figuring he could "fix it up". I cautioned him, but in the end, he filled out the form, paid for the wallhanger and took it home with him. I put on his receipt "Wallhanger. Do not fire." I don't know what eventually happened.
In any case, even when new, some old guns were probably not very safe to shoot. Another example; Colt 1849 Walkers. Very few original Walker Colts survive to this day because the cylinders blew up on the battlefield. Now, remember, this was then a NEW gun and the heaviest one Colt ever made. If you could find a Walker in shootable condition, would you actually shoot it when it wasn't safe to shoot when new? I wouldn't.
In general, trying to restore an old muzzleloader is a bad idea at best and shooting one is probably a worse idea. Evaluating one without even seeing pictures of it is a fool's errand, so I'm gonna say DON'T. Just DON'T.
That said, it is your gun and your life. You do as you wish... but don't stand next to me at the range when you shoot it.