I mentioned in my post for Level 3 that I'm not posting Level 4. It was 4 completely discreet sections, each of which I'll be reusing as sublevels in the new megadungeon.
So here's Level 5. Why is it that the 4th or 5th level always seems to be where the underground river comes into the picture? Well, this dungeon is no exception. I didn't have much planned out for this level in my mind, except that the top left section across the bridge would, I had thought, contain a sort of Greco-Roman architecture and classical Greek monsters (the world above, at the time, was a heavily Viking influenced setting).
Again, with this level, the problem is mostly the size of it. 57 encounter areas. There's also (since I hadn't started working on the level 7 or lower maps) only access points further down to level 6. Of course, by the time characters are 4th to 6th level, they're likely doing a fair amount of wilderness adventure as well (at least going by the Basic/Expert gauge), so maybe a smaller level around this point might not be so bad. You can supplement your advancement to the next character level by doing some exploring of The Isle of Dread or going against the Master of the Desert Nomads.
Still, any reworked version will likely be at least 2 sheets of graph paper, and no less than 100 encounter areas.