Not sure there's an ideal scenario beyond being able to win opening round game, mainly because ISU can't put put together a back-to-back solid performance. But, simulating the rest of the schedule (as realistically as possible), I'd choose something like this:
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We'll be underdog every step no matter what.
But maybe if OU stays 1-dimensional enough and stays in unravel mode, maybe we could still that. ISU has beaten Tech once, so we know it's possible, and any nudge from Hilton South if it's close, who knows?
Similar semi-home-court vs. WVU if they actually take care of Texas (I'd rather have UT and BU swapped 5-for-6 in this scenario, but I don't know if the game-by-game choices are possible).
This is total pipe-dreaming. But OP asked for best-case.