Aluminum Heads

On the E-streets, they are available with either 84cc chambers or 75cc chambers. Being my engine is currently 9.4:1, im not sure which chamber to use. Im assuming that going with the smaller 75cc would put the engine at 10.5:1 or very close. I know aluminum is less likely to detonate but don't know if that's pushing it still or not. It just uses 91-93 octane which is whats available around here.