I've never seen paint really clean up enough for paint prep with a torch. I think you'll end up sanding/blasting anyway. I always use a powerful chemical stripper, ZipStrip. I use it in an open garage when the temp is above 70*F and give it time to work. I use a wire brush to remove the stripper/paint, takes me a few hours to remove all the paint completely.
Here's what I always see after torching the paint, this is silver solder brazing temp, lots of burned paint hanging on real tight: