He was a mass monster back then but now you look and he had a middleweight's back. The delts and chest made him look massive but now he looks "boyish" to me.
He was known for his high calorie, extremely high carbohydrate diet which was uncommon at the time.
Later he was known for pushing the GH higher than anyone else at the time(12iu rumored).
Also early user of insulin, "you use it when you need it" (when on high GH).