Exp. overflow matters not, as characters don't gain/lose levels automatically. You need to gain over 2 billions of Exp over your last trainable level (Exp counts from zero after each level-up in savefile). It means killing thousands of hardest monsters (20,000s+ if you do it in Warzone, but chars will die from old age after so many coming back). So it doesn't fit normal gameplay conditions :))

What does respawn on that dungeon level? Lords of Xeen were finite as I remember, there were just too many of them.

SP might overflow with such approach, you might be right. I didn't abuse buffs. I played WoX with no-well-buffs self-imposed challenge.

I don't count Swords of Xeen as part of Xeen. It was good fanmade game, but it had some nasty bugs and balance issues, nvm overflows.

Edit: sorry for spoilers there, but I was sure this forum supported spoiler tags.