Ron, media blasting is like pelting the metal with billions of tiny body hammers. It work hardens the metal surface and much like smashing a piece of tin between a hammer and dolly, it alters the shape and reduces the thickness. It's not only the heat it generates that damages it, but the repeated blows of the media that effects changes to the panel. How much change happens depends on the media, pressure, angle, time, distance and the operator skill. It also depends how much shape the panel had to begin with. A part with high crown like the top of the front fender won't change shape as much. A flat panel, like a trunk lid will warp in a heartbeat with disappointing and impossible to repair results. Car panels are like mirrors. The slightest distortion shows as ripples and detracts from the appearance.

As Ashtray says, if you could crawl around the car with your camera and post photos, you'll get more feedback from folks here. The first step is to figure out what you have and what it will take to achieve your goals for the car. Right now, we don't know if your talking about a few rust holes in the front fender or a car looking like this $5000 project Camaro at Carlisle.