Congratulations and well done to your son!
I wish I could draw you a graph of the usual pattern of 11+ results! However, there is a huge peak of children who get 141, and then the marks tail off very sharply in the 130s. They rise again to a slight "bulge" around the 121 pass mark.
The score your son achieved is completely irrelevant. He has qualified for a GS place. There are children who score 141 in the 11+ and struggle at GS, and others who score 121 (or get in on Appeal) who never look back.
Celebrate and forget about the marks!