47percent

I've done several worlds with Tekkit using TerrainControl, though I've had to compromise to get it to work. For example, I can get almost all the ores in the game, and the one's I can't get in aren't totally necessary. I can't get oil to spawn on the surface like it usually does, but I can get it to spawn underground similarly to coal veins using the config files in biomes. You can even make it biome-specific that way. And for rubber trees, I can't get the trees themselves to spawn, but using the plants section of the config, where you have things like flowers, tall grass, etc. you can actually put in the code for rubber tree SAPLINGS and it will generate little groves of them similar to those of red or yellow flowers. When you first generate a section of world, the trees won't have grown yet, but they're there and chances are they'll grow eventually. All in all, you can pretty much replicate every resource from Tekkit, with the exception of some Redpower 2 materials. I can get marble to spawn underground in super large veins, but never basalt. Also, the only gem you can spawn correctly is rubies. This is because all the redpower 2 materials share similar item ID's, only varying in the damage values afterwards, which for some reason TerrainControl doesn't seem to pick up. All of these can be added in via the bottom section of biome configs, where you can change or add the spawning of various materials in game.