Slag worked great for me, used it on my 68 firebird. When finishing from bare metal always use a DTM (direct to metal) primer, best would be a epoxy primer, just make sure it can be sanded. Another option would be etch primer then 2k primer, then sand with 240, 320, 400, and so on depending how nice of painted finish you want.Jford is correct. The other concern with sand is it will cut away some metal. It makes a very coarse service that will require either sanding or a heavy primer. You can also get what is called slag. It is a heavy black material that works well on rust and corrosion. Glass beads are a good for most projects as long as the corrosion is only on the surface. If there is any pitting it can take a lot of time and material to remove.
Sand is also a very dusty messy product that requires a lot of dry air pressure. Any water will cause the sand to stick together and block the equipment.