I apologise for my stagnant answer earlier. VBR Bias can be a tough one to get right, VBR is dependant on the movie in question, and 'compression' required, so to speak. Using a higher Bias will result in a more CBR style finish, call it Constant quality.
All I could suggest is play around with it, the only discouraging factor of this will be the mass of time it may take. Maybe start at 50 and decrease in increments of 10 til your happy with the result, people will tell you this setting and that, but its what your happy with. And because your talking CCE SP, be sure to do 4 passes with a lower bias.