If you're going to have your car media blasted, it has to be 100% stripped clean, bare shell, no interior, glass, doors, rubber, drive train, suspension, etc. And, your media blast facility must have a rotisserie and utilize it on your car, and blast every square inch of the vehicle; underside, inside, etc. And, must not damage the large flat surfaces like the roof, doors, hood, etc. To do this your blaster must use high-volume, low-pressure air, light-weight blasting media mixed leanly with a mineral specifically designed for media blasting (not sand) to cut the rust down, and, this yields a slight profile surface whereas your painter will love you for having the entire vehicle prepared properly whereas he doesn't need to sand one square inch to prep the metal for priming.
Expect to pay for this aforementioned service $1900-2400.00 dollars for the entire car, at least this is what I'd charge in my shop, and what I do charge (and get). But, the end state is what you need to be aware of. You must be dedicated to the car and process of restoring it, if you're not, then sanding it down by hand may be an option, but, if you go to sell it, you can command a higher price if it was professionally media blasted, and have documented pictures proving it.
Cheers, my 2 cents!