The carbon spots really are kind of distracting,these old no line fattys aren't exactly(air tight)most likely appeared after grading.
I'd call it 65-65+ but with the "Old fatty" comment will say it's graded 66 (and yeah it's the carbon spots holding it back)
Wear?I assure you it's not.Silver is a very soft metal and also due to the odd composition and quality control issues these can have interesting strikes.
Guessed 65 or 66 and have seen others at 58 and 63 to 66...you say no one has it yet...hardly think 60-62 or also hardly think 67...but will venture a 67 before anything of 60-62