Our last championship run, in 1988, we played three top-10 opponents: Michigan (9); Miami (1); and Southern Cal (2), the rest were unranked. The championship before that, in 1977, we also played only three ranked opponents, two top-10, one top-15, the rest were unranked: Pittsburgh (7); Southern Cal (5); and Clemson (15).
Just for a bit of perspective.