As far as the Avanti you
As far as the Avanti you discribed with the replaced Studebaker engine, I feel that the value of the car is diminished and the soul of the car has been ripped out of it. Part of the cool part of owning a Stude, and in particular an Avanti is to cruise it in the countryside and listen to the 60 year old engine (and in my case the Paxton supercharger) produce a sound and feeling like no other. I own 4 Studes, and they have their own personalities. I'm lucky to own them.