Sounds like you've done your research. Good job !!! The Magnum engine is a good engine for the price. Take a look At the Thunder Tiger as well. Price is in between the Magnum and Saito. I would say the Magnum is a little more forgiving in regards to handling. (OS Clone) But that depends on what experience you've had with Four Strokes.
The radio is a good choice as well for the price. There are others, but your already using JR equipment so stay with it. Can't remember if the 700 offers any model memory? If not you may want to consider one that does. Your budget will help decide that.
Good Luck and Have Fun !!! [&:]