I was just admiring your work over in your journal -- great job! That under floor bracing that you uncovered was spot welded to the floor. You need to either drill a few holes and weld them up (creating new spots) or get underneath and make a few 1/2" or so welds along the edges at 4-6" intervals. That should get it back to factory stiffness.
When you need help with that OD let me know! The most common cause of a non-functioning OD is dirty contacts in the governor and the solenoid. There are two sets of contact points in the solenoid and one in the governor. They get a little burned over time and the OD ceases to function. They usually just need a good cleaning (file/sand, as when cleaning ignition points). If the wiring and all looks good that's probably what's wrong.