Sorry - I was thinking in terms of points, not scales. You make a 97.1 or higher and you pass. Below that you fail.
But I see your predicament, I think.
I don't know what sort of reporting you have to do. Would the activity completion report help? You could do as I describe, with the assignment being a 100 point grade and passing set to 97.1. Then, add a completion condition that a passing grade must be earned. The activity completion report would give you an at-a-glance report of who has passed/failed (as long as everyone has been graded.
Best of luck!