I gotta tell this story, circa 1975, and I had a 65 Mustang. A small hole, just like you showed, appeared in my radiator. My father had just taken up welding and said he could fix this right up. He fires up his Oxy-acetylene torch, lowers his mask, and before you know it, I had a silver-dollar sized hole in my radiator. Well, he did up paying for a replacement radiator.