Cool project. The experienced guys in my club who have shot a great many old guns tell me that 3-4 fouling shots are sometimes needed to get a pitted barrel to start shooting well. The fouling starts to fill the pits I guess. Be extra diligent when cleaning and oiling and you should be fine. If you can seat a lubed patched ball, driving it through the breech, and see good imprint of rifling, and no tears in the patch, it will probably be reasonably accurate.