So let me get this right, so's I don't make a mistook. You intend to shoot a 225-year-old muzzle loader with a 'Damascus' barrel? Or, at least, a twist barrel made of iron, as per the methods of the day.
There isn't anybody here, I hope, who is crazy enough to offer you a load for it - as per the rules of the forum, I believe. Go check and see if I'm right.
At the very least, before you even contemplate firing it with a live load, you should get the barrel checked out for the infamous damascus inter-laminate rust/rot. It is, of course, a converted flintlock if your dating is correct.
tac