Was there a secondary adjustment step to finalize admit/deny? Your heatmap-based method would almost certainly result in an unacceptable racial composition of the class.
But my question about final admit/deny stands. If you look at the racial distribution of the upper performers of any standardized exam (your “heatmap tracing”), it is unlikely to me that a college would be fine with that class composition. Either there must be a secondary layer where your admit/deny’s are adjusted or your acceptance rate must be very high.