The route log that the system was based on seems to agree with all of these.
One other thing I will note is that the designation "SR" itself is a TM invention. MDT refers to these as S-###. Not sure that this is worth doing anything about - the only other US/Canada jurisdiction with a current secondary system is Alberta, and there the secondaries just keep using "AB ###" nomenclature. Still, Alberta has no route number duplications between primaries and secondaries. Montana has exactly one (287), but that's enough to create a conflict if the same thing were to be done.