It shouldn't be difficult to make an engine switch - just drill new holes on the motor dome and install blind nuts. You can fill the old holes with dowel or epoxy and microballons if you want. There is no hinging required on these planes - the ailerons come prehinged with a "live" hinge, meaning the wing skin is part of the hinge. It is reinforced with Kevlar and will never break. The elevator and rudder have hinges preinstalled, and all you have to do is run a wire down the hinges to connect the controls. The cowls are mounted in a typical fashion, with bolts going through the cowl into the motor dome, and blind nuts are installed inside.