Yeah, some racing cars are very much like Trigger's broom...
I've just spent the last few months researching the history and provenance of an ex-Howard Cole Superstox, and when you put all the photographs I managed to pull out of various archives in chronological order, it's bonkers how much the car changed in its nearly 20-year racing career prior to being dumped in a barn and abandoned. It's currently undergoing a full restoration with an aim to return it to its original specifications.
The trouble with the short oval cars of 40-ish years ago, is that they were largely self-built with no traceable identification like what you got if you bought a Reynard or a Van Diemen say, in order to race on the circuits. So it's much harder to establish provenance, especially since these cars tended to go through the hands of multiple owners.
Having said that, Ferraris are a law unto themselves. Not my area of expertise though.
FWIW there's a Jaguar XJR-14 that's been up for sale recently, put together (mostly) from the parts left lying around when TWR pulled out of sportscar racing at the tail end of 1991. And likewise, there's a V16 BRM "remake" built from the original blueprints. Where these fall on the spectrum is up for debate. But never mind that, the howl from that 1.5 litre V16 engine just has to be experienced. (Owwww, my ears!!!)