As a current XK-E owner, I think the key to owning a Jag is the same as owning any other 30 or 40 y/o car, you have to get a good one first.
MG's car was a POS from the git go, no wonder he had problems with it.
My car was originally Primrose yellow with Black interior, I never liked the yellow so I painted it black........
Mine also was a POS when I got it, so much worse than I realized, and I
knew it wasn't any good! I spent the next 4 years making it into something driveable, and it really hasn't been a problem child since, any more than any other 30 or 40 y/o car would be.
If you'd like to read about it and see it, go
here