Please refer to the WREB Candidate Guide in the Periodontal section.
http://www.wreb.org/dental/dentalPDFs/3Periodontal06.pdf
On the first page (41 of overall guide), the Patient Criteria are listed. These are the minimum. While deeper pockets are acceptable, they would not be advisable. The penalties for remaining calculus are severe (pg. 5 in this section or 45 of overall guide). There are no brownie points for an extremely difficult case, only a greater chance of not passing. Make sure you have the proper teeth in the quadrant(s), enough easily detectable calculus, and at least two teeth with a probing depth of 5.
Why choose a patient with 8-9 mm pockets?