The river that provides an exit after the Chaos Lord in defeated in SotSS could enter the area in which PotP is set easily enough, and the Chaos Leviathan of SotSS will certainly come to mind as the players investigate the Pit. Here's what I would do:
(3) PCs find a village near the ravine's edge. They hear about an old tower/tomb/keep/burial mound and hear the first intimations of the PotP. The old whatever they hear of is a minor adventure of your creation or adapted from an older system module, something that breaks the tentacles-to-tentacles feel of the DCC modules run back-to-back. Obviously, the players can choose to ignore the "side-quest" and jump right into PotP, or even run as fast and far as they can from both! In which case, their flight takes them to doomed Hirot.......
Yeah -- this what I was thinking, but it just seemed a little ho-hum. Evil DM was thinking....The collapse of the underground cave and the opening of the passage out of the cave leads to an other-where. They don't start at the top of the ravine... they start somewhere in the middle -- or somewhere underground miles off from the pit -- an Underdark where they find a dwarven village or city or something and obviously various options for adventure -- all of which eventually lead to the people of the pit.
For whatever reason, transitioning from the somewhat epic ending of SotSS to the somewhat mundane opening of PotP *Another* village that has to sacrifice *another* maiden to *another* otherworldly creature? --
Not a criticism, but the three modules have similar hooks. I understand though, hooks have always been difficult for me, as well -- which is why I prefer in media res.
Actually, I think that's exactly what I'll do -- stranded deep underground, still injured from the previous adventure the group is presented with various minor obstacles to reach an underground city populated by strange blind dwarves -- not evil, but different. The People of the Pit become hidden cultists. The pit becomes the city itself with tentacles lurking in various places about the city
and the driving force being that the characters have to find a way to the surface. Some unholy deal may be their only shot.
Oooo. I like it.