I read an interview online about his training split and diet.
He said his diet followed a book called Eat To Win. I guess it was a popular nutrition book in the early 80's. I looked it up online and it was a moderate protein, high carb, low fat guide IIRC.
King detailed his leg training and said in addition to extensions and curls and calves he did front squats, vertical leg press and hack squats.
I followed it and it's really the only time in the past 10 or 15 years that was able to add any size to my legs. After 40 legs just don't grow. But this routine worked better than any other I have used.