go with 140mm and adjust it as needed.
Remember, oil height is final adjustment or fine tuning for your front suspension.
You want to ensure your bike using most of its available suspension travel without bottoming out. Put a zip tie on your fork tube, finds some bumps in the road and try braking very hard over those bumps. Be careful. Nothing special about bump size, regular size bumps that you will encounter on most of your street rides. Add oil to prevent bottoming, remove oil for more travel.
Don't expect miracles as there is no comp. adjustment on the 9er
Put zip tie on while doing the work.
Slowly and fully bottom out the unit, going through the hydraulic cushion zone to hard mechanical bottom out.
Slide down zip tie to fork seal.
Do a wrap of tape immediately above the zip tie.
This is the ONLY way to know for sure where your travel is in relation to hard mechanical bottom out.
You do not want to be less than 5 mm away from that, and 10 is better.
140 oil level is a good place to start, it sounds to be the typical set point for the suppliers, RaceTech uses that, as well as D K, so you can be very confident of the number.
If you get brake dive beyond the amount you want to see, simply go to either 130 or 125 and be done with it. Do not go less than 125.
zaq is right (as usual) do the oil level with spring out.
Be sure to slowly stroke many many times to get the air out of the system before setting oil level.
When you button up your front end, don't forget to do the left fork leg float on the axle once the axle has been loaded up on the wheel bearings.
If you want a written sequence, just say the word.