I see this kind of stuff all the time; I media blast this stuff all the time. What I can say you should do may not be what you can do, or, willing/able to do! So, all I can say is under ideal circumstances this is what should be done to this car -- assuming you have an end state of a nice rust free clean car?
1. Find a Media Blaster close to you find out the following;
-how much?
-do they mount it on a rotisserie? (you don't want them crawling around under it blasting; they get tired quickly, and do a half-*** job)
-what media do they use?
-do they get it all off; meaning the rust, bondo, and undercoating?
-do they have a 'standard', meaning a level of expectations you can expect them to achieve?
-do YOU have a plan after the car is blasted; ie primer etc? Be CAREFUL of the Media Blaster place that offers as a service priming/protective coating post media blasting! I say this b/c 9 out of 10 times they hide the work they DON'T do under primer; and, you can't tell one bit! (This is why I don't paint 'em, I want the customer to see it in bare-metal, they can worry about getting it in paint, if they are totally lost, I can hire a guy to prime it if they wish)
2. Disassemble the entire car, a media blaster is not honest with you if he allows you to keep the glass in, the trim on it, and seats in it.
3. Don't use Soda blasting; it will do nothing against rust, and it has no mass to punch out rust and crud, and it leaves the metal too smooth for paint to adhere to it adequately. I'm not 'dissin' Soda, just saying it has its uses; mold removal, swimming pool clean outs, and graffiti removal, not on car body's.
4. Be prepared to need more metal than you think it needs, the car will come back completely different than as it is now, but, you will be committed to it then, be ready to take it to at least a primer and then primer sealer ASAP as you gather funds for the next stage.
You could be well healed $$ wise to have a professional shop do it, or, you may want to do it yourself for the satisfaction! I appreciate both approaches. But, if you lack the time/$$ like most of us do, you may want to section the car project into sections; strip it down of all the stuff in it/on it. Then secure your blaster guy (stay away from sand), (and yank the top cowel off the lower part of the windshield, there are a lot of spot welds there, but, often, it's a rats nest in there!
Bottom line; GOOD LUCK!!!
