The trigger for NC in version 8.0 should be set before the buggy/incompletable part of the original end game. I'm going to be trying to down the Balor for the 10th time hoping for no crash. I appreciate the concept of having the majority of the new content be after the temple, but for those of us that cannot complete the original game it would be nice to have a work around.
You can attempt to defeat Zuggtmoy without collecting the gems in the nodes and destroying the Orb. The only reason you need the gems from the node guardians (like the Balor) is to destroy the Orb. Destroying the Orb is supposed to weaken Z (but I never noticed much difference) and make her easier to kill --and is part of the original PnP story line-- but not crucial in ToEE. (In the PnP it would have been impossible to kill Z without first destroying the Orb, and the writers of ToEE attempted to preserve the original RPG as much as possible.) Also, according to many opinions in the threads here, Z is an easier battle than the Balor. But the Balor is defeatable. I've done it with different kinds of solo characters many times. It's that d@*!ed Hezrou that gives me problems. Check out the threads here for lots of ideas on defeating the Balor. My suggestion - Prot from Evil and Hit&Run tactics.
The game let me destroy the orb without any gems. Z didn't seem very weakened, though, compared to 7.9 game where I took her on without destroying the orb first.
If you destroy the orb Spoiler Zuggy has far fewer HP and thus she becomes slightly easier to defeat. I've found that the Balor is best handled when you have enough potions of Heroism to go around.
Thank you guys for the responses. After thinking about it for a few days I realized I could get around the bug in at least one of the ways you have suggested. I probably could have searched a bit better. Many thanks, off to Verbobonc.