I tend to agree with you ErwinS. There is no reason why it shouldn't fly with C160 powerplants and there is a chance that the airframe will hang together. There is a chance that the aeroplane would handle much as originally certified. There is nothing in any Theory of Flight that I learned that required specific tags or paperwork. It seems as though we are back to basics here, a one off experimental machine that will require a crew of test pilot abilities to operate it as an non insurable risk. This must somehow be possible.