Give it a good cleaning and see how she looks. Over the years I've picked up a few guns with bores that looked worse than that. It was all dust, dirt and old fouling. After a good cleaning they were smooth and shiny, and I was (and still am) very happy with them.
By the way, my original circa 1922 .405 WCF has the same 3 leaf express sights as this one. When I bought her, the bore was so fouled up it looked worse than the one in your photo. All she needed was a good scrubbing with Hoppes copper solvent and she came out shiny and loves cast bullets.