My web game now supports 1000x larger realms (1Mx1Mx1M) and customized block-style, Huzzah!
This is how I did it:
Volumetric block information is stored in a single integer, and my supported volumetric dimensions are between 1-999 in any direction as you can see in the video.
Next challenge is to make a good procedural generation using the volumetric block information to awesome terrain!