A friend of mine gave me (for free, so that should tell you what he thought it was worth) a 1987 XJ6 a few years ago. As you say, lovely car, very nice inside, great riding. But it ran on five cylinders and would not shift out of first gear until you'd driven it around the block (at around 17 mph tops) for a solid six minutes first.
I did the sensible thing and performed a Chevrolet engine and tranny swap on it, using the drivetrain from a 1993 Chevy Caprice. Runs like a top now. I recommend to anyone who likes these older Jags and can spin a wrench a conversion kit from John's Cars in Texas. No welding or cutting or fabricating required, everything works, all mounts and custom wiring and air conditioning hoses custom-tailored to your specific application, and it all looks and works like it was built that way from the factory. Some day I think I'll do an XJS. They can be had surprisingly cheap, since everyone hates their original drivetrains so much.
As for this burned one, I have to congratulate the building itself on its taste. Those new Jags are absolutely hideous.