As mentioned there is only one rebody available to 'look' like a Cobra, and that is only a slight resemblance. No one will ask 'is it real'
You can put a ford v8 in it though.
My advise is to decide if you REALLY want a cobra replica and if so, wait. Look for deals. Take a HONEST look at your time, wallet and skills. Use that information to do some research and take your time. There is a good used market out there with lots of bargains. Everything from parts, unfinished kits to complete cars.
Add up what it would really cost to buy a clean Miata, convert it, paint it and stuff a V8 in it. Done well it might surprise you.
So get out there, find some owner, go for some rides, look, talk, listen, learn.
These cars are NOT for everyone. Be sure they are for you!
Rick