Auto body repair & detailing: Body Rust, body rust, surface rust

Question
I have an 84' Merc Gran Maqui 5.0 v8, Big car And The Bottoms of the front doors are rusted off, there is slight surface rust on the top of the roof , where a driver and passenger may hold onto leaving surface rust, I got the car really cheap and I dont want to spend to much money on it What would you recommend? I'm thinking of using composites only it would be hard to get the shape somewhat decent on such a large area, About 6 inches off the bottom is missing?

Answer
Jason,
 Hello.  Universal door bottoms are available (at an aftermarket parts supplier).  These will work as long as the inside of the door shell is not rusted away.  These bottoms can be put on with the composites instead of welding.  On your roof, you will have to get all the rust off, using a wire wheel in a drill would be best.  Get some primer called Rust Defender and apply following instructions.  Then you will have to base coat and clearcoat.
Thank you,
Mike and Lisa