I am not familiar with their schedule but I looked up Southern Illinois past rankings.
In 2001-02 they were 28-8. Their ranking got to 11th just before the conference tourney (their highest ever)they were seeded 11th.
2002-03 24-7 seeded 11th.
2003-04 25-5 seeded 9th
2004-05 27-8 seeded 7th
2006-07 29-7 seeded 4th
With that said I would say if Murray State finishes undefeated a rank of 10th would be fair. A seed of 3rd or 4th.