I have nothing to say about actual value - don't know enough about it. But my limited experience with bores that look like that is that they make the gun affordable and don't seriously affect the accuracy. I also never had trouble with fouling, either. My limited experience is one Broomhandle Mauser with a similar bore, one .38 Spl M&P with a similar bore, and one 1955 Model .45 Target with a less uniformly damaged bore. All were OK, and certainly the last two didn't foul excessively. The Broomhandle didn't, either, but I don't remember exactly how much ammo I put through it, so maybe it would have if I had shot it more. It certainly didn't suffer in the accuracy department.

I seriously doubt that the bore will look any better after cleaning.

Hope this helps.