Any extra strength paint striper will work. I used the Ace hardware type(the cheapest) but there are other brands. Sand blasting does not sound like a bad idea just don't hold it to close. You just want to remove the paint/primer not the metal. LOL!
I had basically two options and it was strip it or sand it. Sanding would have been a task to get it all smooth especially in corner areas. What you are trying to achieve is when you spray the first coat of primer you don't have any rough edges showing. When I thought I was done with stripping and sanding I spray the first coat of primer. When I did that I found places that was not smooth and would have looked horrible if it was painted. So don't be surprised if you have to sand on the places you have sprayed with primer. I used it for a guide to what it was going to look like when it is painted. Any areas that you don't need striped or sanded you have to "feather" it back. This would be the taped off places that you are not going to paint to the places you are.
