Is that metal clad wire antique cloth insulated BX? If so, it REALLY doesn't like to get hot, but it also doesn't like being moved. What's the condition of the wires inside the box. If you see cloth covered insulation, then I'd suggest re-wiring it. If it's plastic, you should be safe to pull the box from the rafter and install it bulb facing down, screwing the nail flange to the rafter, rather than the top of the box.
If you do that, replace the bulb with an LED bulb that's all plastic, so you don't risk breaking glass overhead, or just replace the luminaire with an outlet that you can plug shop lights into (assuming it's switch controlled).