The problem with original barrels is that there might be corrosion inside that has weakened the metal, particularly in the breech end. This could well have happened if the musket was stored in damp conditions in a vertical position, allowing moisture to collect in the breech. Such a condition really can't be checked without pulling the breech plug, and pulling the breech plug in a gun that old, even with the proper tools, will probably be difficult without causing damage. For this reason, it's not a good idea, safety-wise, to shoot an original barrel. Exact replacement barrels are available from places like Whitacre's Machine Shop, in Winchester, Va. You can install the replacement for shooting, and then put back the original barrel for the collection.
I made up a hybrid original/repro 1842 musket for reenacting. I used an original Harpers Ferry lock, original furniture, a barrel from Whitacre's, and a stock from Dunlap's. This musket, made strictly to original specs, is much more "authentic" than the current 100% reproductions. In fact it would be hard to tell it from an original.