I have personally talked to Bob about this engine and I have NOT looked at it myself.
I speak from a lot of experience when I say even if the damage looks slight until it is measured there is no way to know if a hone will clean it up or if it needs a bore job. I personally would lean towards boring just because I wouldn't want to risk the longevity of a rebuild on the prep work of the cylinders.
Bob knows his way around a diesel engine as he builds pulling tractors and he would not say a hone will clean it up but he did say the scoring was light however that does not mean it is for sure a hone job to clean it up.
One thing I know for sure is that Bob would not sell it if it was not a usable block.