[my56chevytruck]

I can speak of direct experience having soda blasting done and due to the humidity in the air, it packed into crevices that will take you months to get cleaned out. I'd suggest you DA as much as you can, I wouldn't solely blast surface rust, that's me. then find a good media blaster (plastic/glass beads) and have them go over what you couldn't get to, and make damned sure you get get an "experienced" blaster that has had previous experience in doing this kind of work. If you find much pitting, then I'd fall onto a surface prep and or bondo to smooth the surface before priming/painting.