Found part of my answer on the Minecraft Forums. Was able to just use my own worldgen class to respawn the ore at my desired amount.

 

 

Original Post.

 

I think I more or less know what I need, but lack the over all ability to know how to use it.

What I'm trying to accomplish:

Lower the layer at which Iron Ore spawns and change the number of blocks per vein and veins per chunk.

 

From the BiomeDecorator:

this.ironGen = new WorldGenMinable(Block.oreIron.blockID, ;

and

protected void generateOres()
         MinecraftForge.ORE_GEN_BUS.post(new OreGenEvent.Pre(currentWorld, randomGenerator, chunk_X, chunk_Z));
        if (TerrainGen.generateOre(currentWorld, randomGenerator, ironGen, chunk_X, chunk_Z, IRON))
        this.genStandardOre1(20, this.ironGen, 0, 64);

 

I know what values must be changed:

this.ironGen = new WorldGenMinable(Block.oreIron.blockID, 16);

and:

this.genStandardOre1(8, this.ironGen, 0, 34);

 

Now, I know they're put into/through the ORE_GEN_BUS and that I can @ForgeSubscribe and that I need to write an 'if' to catch the IRON/oreIron(?) when it fires and either over write whats saved, or cancel it and then make 'new'.

 

Unfortunately, I don't know anything else beyond that. Do I make this in its own class and then call it in the main or is it possible to just do it from the main? Would this need to get called/done in the PreInit?

 

I would love to know what you found for a solution!