Glad to hear you got your JD back together. Late reading this thread, but I wouldn’t worry at all about any damage done to the engine. If you had some fluid left in the radiator, you had some in the engine. Those old engines are tough. Top fuel dragsters don’t have any water in them (for a 1/4 mile and the pre-race burnout) although they do have solid castings with no water jackets, which will absorb more heat, vs an empty stock block. But top fuel dragsters produce exponentially more heat at about 9000 horsepower.
I once drove an old olsmobile with a 455 for several miles without water. The engine got so hot the caked oil on the engine was smoking. It didn’t appear to hurt anything, but not something I would recommend.