I've been playing the Skyblock 2.1 map for Minecraft and have figured out there's a way to get Villagers, but only if you can first get a Blaze Rod. In Skyblock, the Nether consists of only a small 3x3x3 block of glowstone and a portal within the boundaries of the Skyblock map, nothing else. I presume if one went far enough in any direction they would find normal chunks (and thus the possibility of Nether fortresses and Blaze spawners), but this would be cheating.
After perusing this question, it's clear that even when all the blocks of a Nether fortress are removed you can still get Blazes (and Withers) to spawn in that location if you just build some new ground there. So, if the valid playable region of a Skyblock map originally contained a Nether fortress, and if the data for the "Structure Pieces" of that Nether fortress still remain in the folder for the Skyblock map, it should be possible to get a Blaze to spawn.
So, the million-emerald question...
Has anyone either found a location where Blazes spawned, or used some method/mod to determine if there are any Blaze-spawnable regions in the valid playable section of the Nether of a Skyblock map?