Scott, On 7/5/1971 in Lacrosse, WI (day after Dubuque contest, two days after Wheeling) Santa Clara won, Troopers were second and Madison third.
Blue Stars were in judged exhibition as this was their home contest (Mississippi Rhapsody)
All three corps you are looking for in that first location, SCV, Scouts and Blue Stars were here (along with Troopers) so this could very possibly be it.