Just a few random thoughts on Harris.
He screwed up in 1984. He held out with the Steelers and ended up going to Seattle. These numbers are approximate, but he was around 400 yards behind Jim Brown to be the all time NFL rushing leader, and had run for over 1,000 yards with the Steelers in 1983. He went to Seattle, and finished the season with 170 yards. Walter Payton rushed for 1400 yards that year, passing Jim Brown, and holding the record until Emmitt Smith passed him.
Harris would have held the record for less than a season, but for all time leading rusher, that would have put him in the same company as Jim Brown, Walter Payton and Emmitt Smith.
In New Orleans, 1978, he owned a couple of Popeye's Fried Chicken franchises. Don't know if he was instrumental in starting them, but I know they started in New Orleans, and their chicken was a lot spicier and a lot better, then. They ran commercials showing the immaculate reception, then cut to Harris holding up a football with some actors in Steelers uniforms holding him up on their shoulders, and he's say, "Let's got to Popeye's!"
All time leading rushers are unusual, especially for their durability. Most running backs go off a cliff after a few years, cause of injuries.
Harris was ahead of his time, cause, as Deion Sanders said, sometimes he made a business decision. He stepped out of bounds sometimes, cause taking a hit that would kill a normal human wasn't worth two yards to him. IIRC, he'd take the hit if the two yards were needed to get the first down, but if he already had it, nah.