Speaking as a lay person, I'd say use the numbers loosely as a rough guide, if at all, and just make events as dramatic as you can. Throw in the sentient, growing void at whatever point it seems like it'll have the biggest impact.
When I played through that module a few years back, I don't remember what clues we had as to the nature of the 'mass', and when we discovered it in the cave I jumped into it, under the impression that was an energy field that held some malevolent force inside.
Turns out there was nothing in there.
Gnome Boy (a.k.a. "Jon") • DCC play-tester @ DDC 35, Feb 2011. • Beta DL 2111, 7:00 AM PT, 8 June 11.Playing RPGs since 1977
• Quasi-occasional member of the Legion of 8th-Level Fighters.
Link: Here Be DCC Monsters