On the disc that I am looking at. the splined hub protrudes more on one side. That side goes away from the flywheel. The other side is marked "Flywheel Side" but stamped so lightly that its hard to find. On some engines, the splined hub will hit the flywheel or crankshaft flange if you try to put it in wrong. Don't remember if that's the case with the Healey.
Marv J