One more thing before I go to bed:
Despite Vader having been deep-fried in a lava pit, Lucas et al. consider the possibility of him growing a gray beard like Ben's in the story conferences. And in Kasdan's subsequent second draft, the unmasked Vader is indeed an elderly man with a white beard. "His eyes do not focus. But the dying man smiles at the sight before him."
Incidentally, there was also a version of the third-draft script with a fake ending distributed, which was meant to throw leakers off. In this version it is Luke who, after going limp while being electrocuted, suddenly rises up to throw the Emperor down a shaft. Later, during the unmasking scene, we get this patently false tidbit:
Slowly, hesitantly, Luke removes the mask from his father's face. There beneath the scars is a horrible mutant, hardly recognizable as human. Luke is repulsed. He throw the mask down in disgust.
VADER
It's too late, Luke, it's too late!
The Annotated Screenplays mistakenly reported this as a real variant of the ending. In this respect it's not unlike the shooting script for ESB, which omitted both Vader's revelation and Luke's loss of a hand. (Instead of outright severing his hand, in this version Vader merely nicks Luke's forearm, causing Luke to drop his lightsaber. Later, on the medical frigate, Luke is seen getting patched up after receiving "a nasty scar" on his arm.)