On a car like this , POR15 and Zero Rust will be your best friend. Preferably por15 as I have used both. I patch welded my inner fenders and engine bay and por 15, then used there tie-coat primer, then a flat black paint. Almost 6 years later and not a single sign of rust or paint failure. I recommend using it on all of the hard to reach areas and inner panels. Especially if you aren't blasting the car.