Not entirely accurate. Gutzon Borglum had only done the head of Robert E. Lee, but it was later removed when Augustus Lukeman took over in 1925 after Borglum left in 1924 over a dispute. After 3 years of not having it completed (coincidentally only having Lee's head done yet again) the project was taken over 36 years later and was mainly done by Roy Faulkner.
Now although Stone Mountain is 90ft tall and Mount Rushmore is only 60ft tall, I would have to say that the width of Mount Rushmore is a lot more than Stone Mountain. Stone Mountain is 190ft wide, but just the noses of each president on Mount Rushmore is 81ft total. I would estimate that the monument is around, if not over, 500ft wide. Now if you want to go by size, Crazy Horse is bigger than both put together, 564ft high.
Not trying to be a dick or anything, just wanted to clear up some facts.