There is no way to realistically talk to all these people for something as short as 15 pages (sounds crazy, I know) and it will take more time than you have to dedicate to the research. If you want to do sixman history, I suggest you refine focus some more. Maybe you want to focus on the teams that have had more than one era of state champion appearances, or focus on a couple of teams per decade, or not focus on any team. It would be a fun read to see where the game started and how it evolved in numbers of schools and rules.
If you do want some people.
Coach Vance Jones (retired) would have my vote as the best ever. He also knows the game from when it started, I think the early 70s. He also won state championships at several schools (which is how I think he proves hes the best). He is also a man character and honest.
Roddie Maddox, not even sure he is alive anymore. He coached Cherokee to state championships in the 70s. Another man of good character. He also coached an athlete by the last name of Belltran if you decide to focus on the great players of sixman. Belltran is often overlooked because his day was so long ago now. Based on old timer stories, he is right in there with the great players we know.
Last thought. If you are looking for a focus, you could easily get stats and records for many of the top players from Lehman. It would be a quick source of information to begin writing from.
Good luck. If you are proud of the paper you write, I would like to read it when you are done. I will offer no critique and just appreciate the work and perspective presented.