Harmy’s primary source is the Blu-rays, so the grain is already massively changed from the start–see below, where you can see evidence that the Blu-ray was scrubbed clean of grain, processed, and then slathered in fake grain:
http://originaltrilogy.com/post/id/901920
As far as I know the only thing he’s doing grain-wise is grain matching, so that footage from an upscaled Laserdisc master blends better with Blu-ray footage (i.e. judicious application of fake grain). The only bits with real grain in them would be the 35mm footage (projection prints, not IP’s or negatives). It’s not Lawrence of Arabia, but the damage wasn’t done by Harmy.