Auto body repair & detailing: Major Rust Spots, rust spots, welding shop

Question
I Own a 1981 Ford Xl Super cab and Its Rusting really bad along The Bottom Of The Cab, There was about a Foot And ahalf hole On The Drivers Side Which i Managed To Fill In, But with The Rust On The cab Panels Im Not sure how To Fill it in so It looks Almost Like i didnt Do anything at All. I Have Full Access To a welding Shop With a Metal Break, And Sheer.  

Answer
You can't bondo the air, my friend. For rust this severe, the only answer is panel replacement. Get online, and find either a used cab, or aftermarket repair panels. Massive rust spots are the hardest thing in bodywork to fix, and make last. Making patches this big is for professionals.