They can be restored to the same level, it just takes, patience, time and $$$$.
In the case of CSX3173, at least as it was before Steven passed, not likely unless somebody has another complete carpet set removed from a brand new 427 Cobra in 1966 and carefully stored it. Or a set of new car take off tires and wheels carefully stored since the mid 1960s. It was a miracle that Steven tracked down new car take off soft trim. I thought it was a miracle when I found, on one of my parts hunting trips, the new car take off set of tires and wheels that were very carefully stored all those decades. The coolant and heater hoses were good ones AC and Shelby installed on new 427 Cobras that Steven tracked down and purchased. How many 427 Cobra owners kept, saved, and carefully stored coolant hoses? Not only did parts hunting mean finding original 427 Cobra parts but some are unique to CSX31xx cars. Or any other of the no so durable parts or materials? Not many most likely. The outer body paint is new but even the license plates were ones the car wore long ago.
Steven filtered the Cobra parts world hunting anything that car was missing and he pretty much cleaned out quite a few former 427 Cobra owners of left over parts. Most people probably won't hunt just the right piece for any missing piece for ten years or more; Steven did on most of the cars in his collection even the Opel Manta Rallye.
Yes you could make another CSX31xx car look similar, I have helped find original and replacement parts for other CSX31xx cars, but with mass quantities of reproduction parts, replacement will work parts including lots of fasteners, and many other replacement materials. New old stock or excellent used 1960s British anything is super rare now. Late summer fall Galaxie R Code engine parts are not stuffed in every old car owner's garage. Parts Shelby American came up with have been obsolete for many decades also.