Gary the torch man at Argos calls that a classic Kona break. The high end ones go, if they do fail, right there on the drive side. No problem at all for a good welder, like the one you've used, to strengthen it with a good solid repair. Now go the whole hog and get it powder coated instead of that beautiful-but-too-soft stove enamel. Someone on here ( Giler? ) does lovely retro decals for bobbins.