The calibration workflow we recommend is to set the Priority at Gray Balance.
The "Printing" Target is the best place to start (Brightness: 80 cd/m[SUP]2[/SUP], White Point: 5,000 K, Gamma: 2.2).
My understanding is the contrast ratio is determined at the end of the calibration process, and is not a setting you select.
Make sure to dim your viewing booth to match the brightness of your monitor for the best on-screen preview and print output comparison conditions.
I hope this helps, best regards and happy printing~ Dana