PC,
What have you tried to clean the cyl up with?
I don't remember seeing any significant discoloration other than flaking of the Nikasil. There is a distinct color difference in plating when it first gets chipped off.
If it was run a while with flaking It will tend to blend in where oil has burnt past flaked off lining. Can you catch a fingernail or pick in the transition from light to dark?
Something You may consider is a ball hone or scotchbrite to clean up the old girl.
I have repaired an old Jonsereds chainsaw from the early eighties that had been in a flooded basement 15 yrs ago.
After scrubbing up the cyl. it was still in great shape. Unfortunately w/out a good photo most guys won't want to give you a bum steer and have a melt down.
You may be able to get an honest answer from a machine shop, sorry PC.