Jeff,
If you need different spring rates for your XKE torsion bars, go here:
Team CJ torsion bars
Dan is a quality supplier of all things XKE (and a few other makes).
One of the most comical stories I've seen emanated from his purchase of a new XK8 around 2000 to use as his own personal car. Recall that he is a top-tier restorer of all things Jaguar as you go along ;-)
If you read this link from the bottom up (start, to the finish at the top) I'm sure you'll be intrigued with his sense of humor and his writing:
xk8
Tom