That said, after studying the Vortex site, this model was designed to be 650 gm AUW!!!!! 

No point in putting any engine on that! a Cox maybe 

And the proposed fuse to make the airframe weight 1 kg is positively unhealthy.

This is what frequently happens on the forum, when the question-poser withholds the full information until the last. Like after reading Ramayana, asking lekin Sita kaun thi?