My uneducated guess is that since you are trying to achieve a pH at the top of the alkaline scale, you can't "overbasify". However, you may have too much lye to dissolve, and may want to look at clean up steps as in a mini-A/B once you have collected your yield.
Sine experientia nihil sufficienter sciri potest -Roger Bacon
*γνῶθι σεαυτόν*