Soda blasting will only remove paint, it is not aggresive enough to clean rust scale out of the pits.
Two options:
You'll need a sandblasting media more aggressive to insure all the rust scale is gone. Then check to insure the metal is still structurally sound with an ice pick. If the pick goes through, time to weld in some new metal. If it does hold the ice pick, epoxy prime.
My preference would be to replace any pitted metal with new stuff. Metal is cheap to install before the paint goes on. Rework gets expensive.
