Rebuilding a totaled car is certainly not fraud. There are millions of cars on the road today that have been rebuilt. If you've never seen the inside of a rebuilder's shop, you ought to see what some of the cars look like when they start. They are truly "totaled," not just wrecked. You would be astounded at the amount of work some cars take to rebuild. They often take them right down to the frame and start over, even straightening the frame or replacing it. SOME, and only some of these cars will have a title branded rebuilt/restored. Most rebuilders will sell the car as a rebuilt car and not pass it off as original. But what happens in subsequent sales is "buyer beware," if the title is not branded.
I can't imagine the incense people exhibit when they surely must realize that most collector cars have been restored... just a nicer word for rebuilt. Are you telling me you haven't seen some of the totally rusted out junk remains of valuable collector cars sold on ebay? What do you think rebuilder/restorers are going to do with those things? Restore and put them back on the road of course.
An example I know the facts of is... an almost brand new Escalade was hit in the front and the frame badly damaged as well as the entire front end wiped out. The insurance company decided to rebuild the $50,000 car rather than total it. A new frame, motor and all front end parts were obtained from Cadillac. Everything else was stripped off the wrecked car and put on the new frame. Because the car was not totalled, it was not considered rebuilt, therefore the title was not branded. The owner got the car back and the insurance company paid the $25,000 or so bill. Is this materially any different than what is described about the Kar in question... no, I don't think so. And it certainly is not fraud.
Let's take an extreme example. Suppose a guy has what's left of a Hemi Barracuda convertible that has practically nothing left but does have the title and data plate. Consider that a complete one may be worth say a million dollars. He buys a donor car and a scrounges up a whole lot of parts and as faithfully as possible rebuilds the car. Are you saying this is fraud? Wrong. It is in fact, a rebuilt Hemi Barracuda. Is it the same as or as valuable as an all original car? No, of course not. An honest seller would represent the car just as it is... restored... and the buyer would have the responsibility to determine just what the extent of that was and determine what the value to him is. What is this car worth? Who knows? The market place will determine that.
Now where the fraud part could come in is if the seller, any seller who knows he is misrepresenting the car, represents to a buyer that the car is something it is not. If a seller stated to a buyer that the car was all original sheet metal, the odometer was the original low mileage, all matching numbers or it was a one-owner never wrecked car... that sort of thing... that's misrepresentation which is fraud... if you can prove it in court, which is difficult.
I vote for taking the K inner fender and title, a donor Mustang... or a couple if necessary, scrounge up all the original K parts possible... hopefully a genuine K vin motor and trans and rebuild/restore the car.... exactly as proposed. And I see NOTHING wrong with it. That puts a rare and historically important K Mustang back on the road for someone to enjoy. In the sake of honesty the seller should document what is known about the car and pass it on to the buyer but there is no legal requirement to do that. Certainly the seller should not misrepresent the car and should answer all questions honestly to the best of his knowledge but again... no legal requirement to do so. And don't anyone bother to get upset about this because I guarantee you that there are probably a million (a few thousands more or less) collector cars with no more pedigree than this car would have. You might even own one.
If a buyer wants an original K Mustang rather than a restored one then he should gain the knowledge to tell the difference... it's really quite easy to tell what's been done to a car... it's virtually impossible to rebuild a car to look as good as original.
A person should take due diligence to determine just what the car is and is not and pay accordingly.