If you have good gas (92 oct or higher) available, you should be able to run 11.5:1 or 12:1 compression as long as you have a good engine management system (programmable). If you build the motor right, N2O and high compression love each other.
You should consider Darton sleeves if you want to spray a lot.
Octane booster is a waste of money. A can of it bumps your actual octane by a fraction of a point.
You might talk to Norwood Autocraft about building a motor for you. The last time I was there, they had a wicked 2.6L H22. Their number is 972-831-8111. They do great work. Mostly Ferraris, but my friends and I have gotten them enthusiastic about Hondas.