Hey fellow Troopers, I've got some questions for you -

The Trooper itself


Quick backstory - My dad has a red 1990/91 Isuzu with the 4JB1 (around 300k KMs) engine, bought new, which has been sitting (but used for very short trips (less than 7km per trip) about 4 days a week) in all the nasty types of bad weather (no snow / salty roads) for the past 20 years or so. Goes without saying that it's accumulated a hefty amount of rust - the whole roof, 2 holes under the windscreen (which i've filled up with some compound).

However still starts up every single damn time and hasn't been worked on for a very long time...

Fast forwarding...I'd like to restore it - removing the rust, repainting etc....
My dad's a mechanic himself so mechanically related problems can be sorted with ease.

Why would I want to restore it? - Sentimental Value

My questions are -
1) Where are the areas that are most prone to having a ton of rust that would (economically) kill off the restoration process?
2) What would a ballpark figure look like of the costs (will be taken to a body shop) that I would incur to de-rust and repaint fully?
3) Has anyone ever done this?
4) Write down anything I should look out for


Thanks!