If you have one of the small siphon feed sandblaster, you would be better off finding a headstone manufacturer or professional media blaster. Doing this job yourself is not one of the more rewarding ones. Locals in my area will do a frame for about $25.
Siphon units clog easily (have never used one of the pressure pot ones), the sand gets everywhere, in your ears, mouth, nose, etc. You will need a space outdoors where you can do the blasting on a DRY day.
If you still wish to do it yourself, I would recommend a crushed slag product. The one I have for small parts in a blast cabinet is called "Black Beauty". It cuts paint rapidly and doesn't leave the surface too rough. Silica sand can be used but in my experience cuts slower. BE CAREFUL! Silicas can cause respiratory problems, so if using those wear a good fitting mask.
Be sure to shoot a coat of primer immediately after blasting as rust will start with the least bit of humidity.