I could be wrong, but I do not think mint sets coins got their preferential treatment until the 1980s. That is, they were minted and handled just like any other business strike.
Also, those mint sets are made with a non-rigid plastic. It would not take much to transfer any contact though them to the coins.
With all of that being said, the photo says MS-64 to me.
Also, those mint sets are made with a non-rigid plastic. It would not take much to transfer any contact though them to the coins.
With all of that being said, the photo says MS-64 to me.





















