The saving grace - imho - is that this car was built back in the 60's.
The description mentions that the car was "campaigned in 6 road races before being sold". Why would the owner have stopped after 6 races? And the next owner wanted a show car/drag car? My gut says the road racer was crashed and then bought to be built into the show/drag car.
My guess is the car was destined for the scrap yard if it hadn't been purchased. Back then it would have been "just" a wrecked Jaguar.
Now, again imho, if someone was to do that today to an XK140....well that's what frontal lobotomies are for!