I bought many rifles from CMP. I always choose to buy a SG (Service Grade) rifle. Back then, there were only 4 grades.
As for "SG - Special"?
Whatever. I'm shooting mine.
IIRC.....some SG rilfes were sent out with new CMP stocks (no extra charge). Because, for whatever reason, the original stocks were not up to grade. And, some folks were not exactly happy with getting a "new stock."
That all being said.....
Your rifle looks like a whole bunch of new or close to it parts.......that's good for shooting.
Your barrel date is a late date.....that's probably goes to condition, good for shooting.
Your rifle has got a new stock.......that's a good thing for a tight lock up and shooting.
From your pictures......you have a BEAUTIFUL rifle.
So, get out there and shoot it. Don't forget to come back with a range report.
Aloha, Mark