As always, John is right. It is not an original first generation Camaro motor. What you have, however, is a potentially great "street racing" machine. The great thing about a small block 406 is that it has "street manners" (torque, rpms, etc.) but it is really a racing motor (depending on how it is set up... may have 600+ hp).
What else can you tell us about it???
Here is another article about the 406: http://www.carcraft.com/techarticles/68999/
By the way, THE decoding book for first generation Camaros is: Chevrolet by the Numbers: The Essential Chevrolet Parts Reference, 1965-1969 Alan L. Colvin. By what John said above (no 406 until 1970) it may not help you much on the motor, but it is a wealth of info. about the rest of your car. There is a 1970-75 edition.