Ok so I did some math. Then I poked some blocks. Then I tweaked it a bit. And heres what I got.
(Edit: Updated the world save now with more options because I'm crazy like that and Sleep is but an illusion to me now)
(Update 1.3 : Added "GrimBlock How To" world save with a basic example set)
GrimBlock 4x4

2012-04-17_10.49.44 by Saice, on Flickr
GrimBlock 5x5

2012-04-17_08.57.49 by Saice, on Flickr
GrimBlock 6x6

2012-04-17_10.53.30 by Saice, on Flickr
Extra shots of 5x5 you get the idea 4x4 and 6x6 look much the same.

2012-04-17_08.57.22 by Saice, on Flickr

2012-04-17_08.57.03 by Saice, on Flickr
GrimBlock is a set of Minecraft world saves and MCEdit schematic files. In the Zip below you get three superflat worlds and six schematic files. three single floor and three 13 floor schematics for importing via MCEdit. These are all superflat with structures turned off and set on Creative. Some Editing skill will be needed to get full use out of these.
Some numbers.
4x4 : Each floor is 128x128x8 thats 32x32 Cells of 4x4x6 with a 2 block gap between floors.
5x5 : Each floor is 160x160x8 thats 32x32 Cells of 5x5x6 with a 2 block gap between floors.
6x6 : Each floor is 192x192x8 thats 32x32 Cells of 6x6x6 with a 2 block gap between floors.
Why 6 high? Well 4 high space is pretty large from a Minecraft point of view but your floor and ceiling take up 1block each so 6 high is really only 4 blocks on room space. If need be you can make vaulted ceilings by using some of the 2 block floor gap between the floors.
The core schematics for 13 floors are
4x4 : 129x129x105
5x5 : 161x161x105
6x6 : 193x193x105
The extra blocks are from a spine I used to line them all up.
So its all ready to rebuild Grimrock or any other dungeon you want.
https://rapidshare.com/files/3644761963 ... ck-1.3.zip
Enjoy. I'll be working on my own.