Instead of removing rusted metal in chunks and small parts until you get to quality base metal, look over what is crap and see if your better option may be removing a larger section and fabricating replacement part. Drilling out factory spot welds with either sporweld remover or a drill bit isn't that terribly difficult. As a bonus those holes made by drilling spot welds out gives you weld attachment areas. Sometimes you may find good metal with a pin hole or a large gap requiring filling. If you use a piece of brass or copper as a backing piece while welding, it will help fill that gap/hole easier with less heat and distortion. The copper or brass isn't weldable so weld wire/stick will not "weld" to it. Additionally the cool metal will solidify the molten steel to help fill the gap quickly. Another trick is to use 7018 or 6010 1/16" welding rods with the flux removed (smack it with a hamner a few times and it strips off easily but do not remove the fine flux still adhering to the rod) as filler rod. While mig or stick welding use that as filler material utilizing your none stinger hand to feed it into the arc.
