Cassius
I'm unaware of any drawings on the Web for the ever popular Cobra,
and there are over 10,000 replicas of that car sold !
Chassis design/fab is not something you want to mess with if you don't know what you're doing. You're risking your life, your passenger, and maybe the guy you hit when something goes wrong.
I also suspect a reason is that there are so many affordable Cobra kits,
that it just doesn't pay in terms of risk vs cost. The problem with the GT40,
especially in the US, is that there was never a low cost accurate space frame kit available. In the UK, Tornado sells a nice affordable chassis/body starter kit, but with the US Dollar so weak, and transportation/import costs so high, it adds up to being an expensive proposition.
Being an ex-Factory Five Cobra owner, I had hoped they would do a GT40,
but they agreed not to as part of their settlement with Shelby.
That was a darn shame in my opinion, as I doubt anyone else has
the resources and will power to pull it off.
But I digress. If you have the skill and brains and desire to do a home built
GT40, I'd first obtain a body and mock up the chassis underneath it in wood,
then make your drawings and duplicate in steel. You should check out the websites of some of the home-builts to see what's involved.
One of my favorites is
The Kimini 2.2 car project.
Good luck.
MikeD