Based solely on finishing Gary Hart's book literally 10 minutes ago, I think I could make a pretty good case for his inclusion: Manager for countless main event, money-drawing talents in various promotions from the 60s through the 80s. Memorable and entertaining character. Successful booker in Georgia and (mostly) Texas for several years. Responsible for developing many wrestlers into main eventers and coming up with/being involved in many memorable angles that drew money. Successful TV producer...
I'm no expert on his work. I only know of him from YouTube, a few tapes here and there, and the old Apter mags, as he was not part of the TV wrestling I watched in Calgary as a kid during the 80s, and was pretty much gone from the scene by 1990. But from what I have seen I think he was an exceptional promo guy and excellent at getting over characters and feuds. I'm actually kind of surprised he's not already in, but I guess the strikes against him are not having a run in some major areas, like New York, St. Louis, etc, being gone from the scene for so long, and usually being only a manager in the areas he did work. However, just to use an example, and not to rile anybody up because I'm a fan of the guy, but if someone like Heyman is in, I think Hart (who I would say was more successful than Heyman, but not as influential) should also be in.
Thoughts?