If you are going to create a masterpiece you need to start with a good foundation. The best donor cars are cars that most enthusiates think too nice to make into a transformed 911. Many back dates are built on salvage cars or wrecked cars or bent cars that should be in a junk yard. In fact more than one backdate was done on a car rescued unwisely from a junk yard.
This car, the donor car, was a beautiful 1980 SC. Why such a nice car? No issues with rust or a bent chassis crabbing down the road. It is much easier to restore an un-bent car with no accident history and low miles. Porsche started dipping their chassis 4 years before this car was made, so this car should be rust free for many years to come.