Hey Lamb, from the photos it looks like the curvature of your top tube is too great to allow this type of tank to seat properly. These tanks are designed so that most of the stress is between the length of the tank tunnel and the corresponding length of the top tube. The mounting bolts are simply there to create some grip to hold the tank in position. If the curvature of the tube is too great, when you tighten the bolts they flex inward to compensate for the curve putting excessive stress on the solder joint and invariably the joint fails. It doesn't matter what you do, if that stress is not relieved the same failure will result. When I encountered this on one of my builds I fabricated a bracket that raised both ends of the tank above the highest point on the top tube and after many miles, no leaks. The other alternative is to get a tank with a deeper tunnel, or as has been suggested, get a Whizzer style tank that mounts differently. One thing is certain, a gasoline leak on a vehicle is dangerous. Good luck.