I think the honest answer was posted above.
But... alway being up for a challenge
I think that the detailed answer is that it is possible. And has already been done.
E.g.
http://www.xk180.com/
I've seen one of these part-built and it was based on exactly the same premise that you are considering. i.e. strip off all unnecessary bits and bolt on a new body.
Admittedly, they also chop their donors in half and shorten them first, but even that is not outside the realms of a VERY careful and properly equipped builder
But don't rule out the other option where you could custom build a space-frame and then simply reuse the Jag suspension and running gear and if you go that option then you'd do well to read up on how the Ronart was developed:
http://www.ronartdriversclub.org.uk/...w152mark1.html
And also have a look over at Nostalgia cars for inspiration
http://www.nostalgiacars.co.uk/cars.html
No matter what you do, if you do take the plunge then please make a build thread so that we can all nosy/discuss/steal-ideas
Best of luck!
Dave