Honestly, for a HS kid who is 15-18, pointing out a championship from nearly 40 years ago doesn't move the needle
I'd argue you need to focus on the recent past. We're all older so 1984 means something to us, but for a HS kid it's about the same as TCU or Yale or Army bragging about their national titles.
Army won their last title in 1945 (39 years before BYU) and Yale won their last title 36 years before that (1909). But it's been 38 since our national title, so to a 17 year old kid, they're all ancient history.
SMU can make a lot of the same claims based on their dominance in the 80s.
This isn't to diminish those things, but to point out that talking about ancient history (to a 17 year old) doesn't accomplish anything. It's like me bragging that I could dunk 20 years ago. Gets nothing more than a "Sure, old man"