Only if you're talking about the original steel-bodied Tonkas.

It is part of our natural drive to always make something better. Kinda like making any food better by adding bacon...

 

Difficult to see getting an XK8 light without major surgery, unibody car so it's got heavy bones.

If you're willing to go through the trouble of making the body, the FFR GTM is body on tube frame and has nearly the same dimensions, 101.9" wheelbase and 74" width. 2400 lbs with a stock crate LS7 nets 3.0 sec to 60 and 6.6 sec to 100mph. Swap on a lightweight XK8 body and have quite a sleeper. But it's not an XK8 anymore of course.

https://www.factoryfive.com/kits/gtm-supercar/design/

 

Arden had created a lightweight, but as with everything Arden, it is very pricey. Here are a couple of articles:

Arden Jaguar Lightweight A-Type RS - Tuned - European Car Magazine

Arden A-Type Lightweight RS

And from Arden a carbon fiber body kit, not sure how much weight this saves.
http://shop.arden.de/jaguar/a-type/a...fk-carbon.html

 

You would lose about 140 lbs! Check out this web site:
Jagar XK8R Wide Body
Looks like the answer to your dreams. And not off the chain pricey either. So with other mods like removing some mufflers, and the useless rear seat, you might be looking at minus 250 lbs. With a really great looking car in the end.