sorry for the simple reply, but it would be usefull. go to www.nitrorc.com
you will find the answer there.
my recomendation is to call the manufacture of the engine and ask them on stock settings with nitro %, most of them are setup with 20%. once your car is running have fun with it. ask your local fast guys for assistance.
You won't get a simple answer to your question. what you are asking takes years of testing and experience. "can't expect to be given a degree without the work"