The minimum hardness correlates to the minimum required tensile strength for your part. For example, an API 75k material designation has a 95ksi tensile requirement. So your minimum hardness would be about 197 BHN and you max would be aboud 235 BHN (= 250 HV or 22 HRc).
API doesn't get into hardness for austenitics, but you should be able to find them in an ASTM spec. try ASTM A182 for forgings.
The bottom line is that hardness is a direct representative of the tensile strength of the material.