J'ai trouvé ceci comme explication. (lien plus bas)

"Sympathetic restoration" is a standard term and concept out there in the worlds of antique furniture, antique toys, rare books, and other things I play with besides Porsches. It means that if an item needs repairs, you do them. if original or repro parts are available you use them, with no attempt to deceive. If no replacements are available you restore the item to look and function very similarly to original, though obviously not identical. Hemmings even has a definition in the automotive context: "Somewhere between fully restored and all-original is the sympathetic restoration, usually implemented to preserve as much of a car's originality as possible, while preventing it from damage and deterioration."

Je propose "réparation de bonne foi". Je n'ai pas trouvé de référence sur le net, donc ce n'est qu'une suggestion pour faire avancer la recherche.

English term (edited): sympathetic rebuild

Exemples :
En 2001 : reconstruction totale conforme aux spécifications d'origine
Entièrement reconstruite en 2001 selon les spécifications d'origine

Conforme à l'origine
https://ffve.org/files/docs/Manuel Examen pour Concours d Et...

Il y a une différence entre reconstruction et restauration

car il y aurait un tendance allant vers la restauration d'origine ,mais ça reste à ... The Henri Chapron D 6 would benefit from a sympathetic restoration.