Does the door (s) sag so that you need to lift at the handle to close the door? Check if the ridge below the window in the door lines up with the same on the on the body . You can adjust for some sag by loosening the 3 screws on each hinge where it attaches to the body and where it attaches to the door the holes are over size to allow for some movement. Try them on the body first then on the door. Don't loosen then all at once. If the door is too high then the adjustment works in the opposite. It is possible the hinge pins are worn and there is an over size kit I have seen somewhere to replace the pins.
At the striker (handle )side the receiver also has oversize holes in behind, you can loosen the screws and align the stiker to the latch. Assuming no major frame rot or damage from an accident causing the misalignment or as you suggested bad welding job. There should be enough adjustment to give you what you need. Hope this helps
Steve