Think we're mixing selling a winning car without all the winning parts and showing a car with parts from different sources. Not sure if this is going to read as I expect it to be read but I'll give it a try
IMHO it's not "cheating" since the rules don't require all the parts to be original to that particular car and since plenty of parts are removed, replaced and so on during a restoration. So this seems to be only about (in the showing part of the discussion) when they were changed, added or replaced. BTW the rules don't require you to even own the car - theoretically you could borrow or rent a car and show it. Yes its been done.
Is it "cheating" to blend in new metal into another panel so that it looks untouched? Or using a quality reproduction part in place of an unfound original? Is it the source of the parts that makes it "wrong"? Can I take a better part from another one I own and use it on the car I'm showing and never remove it?
At this point I believe that a judge is asked to evaluate only what is presented to them - at that moment, with no regard for how good or poor the car was when it started the restoration process, how much money the owner had/has or in fact anything about the owner or restorer. The car is what it is and the rules guide the judges through the limitations spelled out in them
IMHO at this point its not my job as a judge to concern myself with where the parts came from, how much was paid for them or what will happen with the car once it leaves the show field, after the event, show ....... I can have my opinion - but after the show that is all it is. But I guess this new question is not directly aimed at judging a car or the award but the choice an owner or restorer makes. Making policing and the judging aspect moot.
Think this line of discussion will only lead us to opening a can of worms many of us have been down before. Fun for a little while, discussing the possibilities and unanswerable questions, but to what end?
Now the whole selling a "award car", without all the parts, that made it an awards car without full disclosure is a completely different subject.
Just me - and I respect that others may have differing opinions
Oh - did find the use of the term "cobbing" and interesting one.