I think your expectations concerning power band are a little out of line with an open chamber head and flat top pistons. Max RPM is going to be 6500 Max, with peak power coming in around 6000 RPM. With the juice on, you will probably shift around 6 grand.
You need to stay conservative when it comes to cam choice, and that is due to your lack of static compression. If you choose a nitrous designed cam, it is going to sport a wider lobe separation angle, and that will make the engine a little more flexible and more suitable to the lower compression ratio.
My choice for your engine would be a Comp NX268H, nitrous grind. It will still run well without the juice on. If you go wilder on the cam, it's going to be a dog when it's off the bottle. You have enough stall and gear, along with the light weight, it should run well.