This map connects with left side of the previous map. The upper sub-level (aka my one hour dungeon), probably attached to room 17 or 19. One of the rooms in that area. Image contrast has been adjusted for ease of viewing.
I also drew the corner connector map that didn't quite fit on either the above map, or the one I posted earlier.
You can see where this map connects with the above map at the C and D corridor and with the other level 3 map at it's hallway D. You can also see where there was more dungeon that was lost to whatever caused it to collapse.