Wow. If it does not have PCB's and burns OK, it sounds like a winner.
Maybe try a quick lube test on it, get a 3 like bearings, wash all grease out of them, chuck one in a vice and spin it with a heavy heavy load, you want it to size and gall. give it a while and time it. Next bearing, lube it with your transformer oil, see if it lasts longer, 3rd, lube with pump diesel, see how long it lasts. transformer oils are purified to take long term high temps and not attract moisture. Lube qualities are unknown, but likely still present.