Deleting Chunks in Tekkit

[GreatGarfield]

Good evening,

My Question: I was wondering whether someone knows how to delete chunks in an existing Tekkit 3.1.2 world.

The world I use on my server is my trusty old map which my friend and I use since Beta 1.4. Now we made the move to Tekkit and I'd like to delete certain chunks, so that the newly generated chunks would contain shiny new Tekkit ores. Since the algorithm for map creation got updated two times or something already it will look strange, I am aware of that.

Thanks in advance