How about Richard Wagner's "Ride of the Valkyries" when the Griz come out of the tunnel? Yeah, the Valkyries were women, but what the hell? Play it on the loudspeakers. The school song will be heard often enough thruout the game. I'm not putting down "Up With Montana....," I just think that the Griz coming onto the field is something of epic proportions, every game, like Wagner's operas.
Maybe play it just before the Griz come out, so the band can play the school song as the guys go by.