Okay, thanks for clearing that up. You didn't goof!
As for the 8 yards, he gained those 8 yards without the benefit of a foul and is entitled to them.
Change the play:
There's a 5 yard face mask foul on the runner at the 36 yardline for grabbing a facemask on a stiffarm. The result is the same. Mrk off 5 from the spot of the foul, he gained the 8 yards without benefit of the foul. He's entitled to them.