Go easy with the wire wheel, you can "work" the surface of the metal and it won't look uniform when painted. I would glass bead blast or chemically strip the paint. In the tight spots or where the paint might be double coated apply a second coat of stripper and power wash it. If the stripper does not have the skull and cross bones on the container don't buy it. You want the stripper that if you get it on your skin you are headed for the sink to wash it off because it burns so bad. The kind we use has an airplane on the container, I think it's actually called aircraft stripper.