Well, so far so good, although it hasn't gone quite as planned.
The Rahib, instead of being a 5th level cleric, was a failed polymath (mystic 36, mage 30, cleric 20, thief 18). Incredibly powerful beast, 350hp, follower of the Master of Hule and wicked beyond measure (but I had envisioned him as being quite personable, socially).
I had expected the PCs to talk to him, reason with him, try to sneak up on him... I positioned him in such a place that he could escape if need be. I didn't see one of the fighters charging straight at him in
haste, falling over and breaking through the trapdoor that was the Rahibs main escape route while the party cleric cast
dimensional anchor at him, a spell of his own devising that for a short while prevents teleportation (the Rahib rolled one on his saving throw!).
What followed was an epic fight, in which the Rahib eventually died. Took some luck on the part of the party, and of course some skill and sheer determination. One fighter got knocked out at the start, the mage went down, the other fighter got killed early on, the thief
mazed, the cleric barely had two hit points to rub together by the end of it... But by completely mobbing the Rahib, with the cleric keeping enough party members standing to finish him, they eventually got the better of him (although not before he had had to
cureall himself twice, thus the total damage he took exceeded 600...).
Ultimately all you need to change is a couple of the encounters; the three witches are going to be equivalent to the three crones in Norwold, only all intensely evil, and I'm going to have one as MU36, one as CL36, one as F36.
The acolytes (siswa, low level elves) are more challenging for the PCs just as they are; they turned up expecting a major fight, and its actually really hard to avoid killing them. Some of the other challenges there (teleport traps, old fashioned dungeoneering things) are as challenging to the players now as they always were.
They've just discovered the two surviving prisoners... One of them I've modified to be a high level paladin of Al Kalim. Should prove interesting