Sand blasting the frame would be fine. As stated above make sure any moving parts are properly covered. also freshly blasted metal will rust quickly so be ready to prime anything you have blasted at the end of the day unless you are working on the frame in a place that has low humidity. Also a quick note Sandblasting sheet metal (doors,fenders ect..) can warp it. They do make a few different types of beadblasting media that you can use on sheet metal that will not warp it.