Economic viability comes into it if the aircraft’s value is worth half what it would cost to rebuild it. Why would you spend way more than the aircraft could ever be worth? I’m rebuilding an Auster here in New Zealand and I’m doing as much of the work I can myself (under supervision since I’m an engineer just not an Aircraft one). It’s from the ground up and if I paid someone to do it it would be waaaaay over NZ100K when they are selling here for barely NZ$50K. A totally rebuilt one might be worth a bit more but not over 100K. And mine had major repairs done to the fuselage and one wing by the previous owner so I’m not having to do major repairs whereas the Chippie needs major work carried out by someone who knows what they are doing and is licensed. If money is no object and the owner wants to see her fly again why then of course economic viability goes out the window. That’s from the heart and there’s no price on that! :p