The syphon blaster is what I used to do my sheet metal and the frame crannies but it will be slow and prone to clogging unless you have a rather large compressor to power it. If you are in a hurry I would recommend finding and buying/renting a pressure pot type blaster. You will need to use care on the larger/flatter sheetmetal surfaces or it WILL warp on you.
I would recommend getting an angle grinder and a knotted wire wheel instead. The wire wheel will make short work of your paint and major rust after which you should sand it with 80 grit to profile the metal prior to priming. Either way you go, use safety goggles, a good respirator and make sure others are not in the area.
