Well if you do indeed decide to go through with this, do something unique.
Why go through all the work to end up with a friggin mitsubishi at the end?
Building a car from scratch means you can think outside the box.
Something like what this guy (18 years old) did. Couldnt afford an Ariel Atom so he built his own.
http://www.flickr.com/photos/25435483@N00/