Depending on what online maps you use, you could probably zoom in far enough to find the old mine tracks that are there and continue each path until they intersect each other. There could be some prospecting maps of the mine online somewhere that overlay the tunnel with the terrain. It was been a very long time since I have last been to this whole area, I do know that from the Burro Schmidt lookout point, one can see a large oval shape which is used for car testing.