I'm no expert by any means but here's what i'm doing and how i would start with your tank
i'll be getting some q5s for my 90 gallon within the next week and plan on using 60 degree optics. i'll have a total of 48 (50:50 whites to royal blues) leds over the tank to start and will add more as needed. before adding more i'll play with fixture height, degree of optics, less dimming etc to try and figure out how to best suit my lighting needs.
with your rockwork being in the middle of your tank i would start off with 24 q5s, 60 degree optics, 12 white and twelve royal blues and add more as necessary only after playing with optics, drive current, fixture height etc...
i'm doing the build along with some friends with different tanks and different lighting requirements. i'll be posting many pics of the setup once we get the leds in and get our project started. btw we ordered our LEDs, meanwell drivers and optics from nanotuners.com (will follow up on that with a review of there service once we get the package).