A word of warning about the motor box design.
The Great Planes motor box design is flawed, and will separate from motor vibration, etc. You will need to reinforce the box with fiberglass and epoxy.
There is a tech note on the GP site about this flaw, and how they recommend repairing it.
I also know of this flaw first hand, as I have the GP ASF of the DR1. Kept breaking the mount until I did the fiberglass and epoxy repair.
There is even a video of the this actually happening during flight about 1/2 way down the linked page.
http://www.rcgroups.com/forums/showthread.php?t=657521
I would like you to seriously consider reinforcing the motor box.