I don't see why it wouldn't work just fine, Tom. You could quite easy to make a wooden float - type cutter/scraper.

If you can get your hands on the book by Ned Roberts "The Muzzleloading Cap Lock Rifle" you can see how to make a rifling bench quite easily.

A single groove in the dowel-type guide would work. Multi grooves are not necessary. A gently twisted 1" or larger square tubing could also be your guide. The tubing idea would be fiarly easy, with a cast-on plug of lead for the cutter guide to turn the float.

The gentle twist would be easy to make with one end of the tubing anchored, the pipe heated over it's length and then twisted - slightly. About anything around 1/4 turn over 24" to 30" should be a big improvement over a smoothbore.

That barrel would literally call out for a patched ball - clean, accurate shooting - with black powder.