sandblaster or wire brush + rust neutralizer?

There are openings on each end of the cowl for drainage. The water and debris is supposed to go out and down inside the lower rear of the front fender.Then if that gets stopped up you may have to remove 2 body bolts under there and pull out on the fender a little. Rocker moldings prevent this action.
I haven't had to deal with severe rust. I have had small water leaks.
I replaced the wiper pivot seals and vent box seals when I had the dash out.