When I have to cut out spotwelds, I think ahead about what will I have to weld back in. I don't like the spotweld cutters that look like a mini hole saw. They make too big of a hole to have to fill back in, making warpage more likely. I use a 5/16" drill bit because it tends to self-center in the spotweld divot and leaves a hole just big enough for me to heat the metal in the bottom piece of metal with the tig to get it cherry red so I can add filler wire there before adding wire to the top piece of metal. Also, if I accidentally drill all the way through both pieces, the hole is small and easy to fill as compared to the spotweld cutter hole.

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission