If you are dead set on running just 87 octane you can just stick with 8.0 but how much more is getting higher octane gas 10 cents 20 cents more a gallon, and how often are you going to drive the car, every day daily driver?
I would just run 91 octane and not worry about any detonation, run alcohol injection , some type of boost timing retard device. Is an intercooler an option for you?
Not sure of all of your goals for your vehicle, just drive it on the weekends, car shows, daily driver, what gear ratio are you running, manual trans, auto, car weight etc all have to take into consideration when planning a turbo car project.
