Thank you, though I already am aware of that pack and integrated some of its great (OreDictionary) MT scripts. It also uses CustomOreGen from what I know but I don’t think it ever modified the default GT6 module (I’m unsure if it ever even used it). I think what it also did is have raw ore spawn in these groups of stones you could pick up (or at least that is what happened when I played with its configs, might just be a new feature of GT6 I’m unaware of, though EDIT: looks like it is). Many other (as in non-TFC) materials were delegated to other dimensions, partially due to gating, I believe.
Yes, however, a GregTech6 module is activated by default, see CustomOreGen/src/main/resources/config/modules/Gregtech6.xml at master · lawremi/CustomOreGen · GitHub. The reason why I am reluctant to use it is because it’s 4 years old and I am not sure if it covers everything you need for GT6 progression nowadays, yet it still is obviously better than nothing because, without it, only everything besides small ores and ore veins spawn (save for bedrock ores, which makes progression rather impossible.
Here’s what its GT6 oregen looks like in practice
as you can see, it overrides TFC worldgen and spawns GT6 stone ores according to the config. This still isn’t as good as Greg’aFirmaTech’s solution using CoFHWorld, though, which you can see here
I have never tinkered with CoFHCore, so I don’t know what is happening exactly, but it looks like GT6 rock layers overwrite TFC rock layers and CoFHCore is scripted to include TFC rock layers as large veins. Obviously not perfect but fairly good. I’m not sure if that also screws up GT6 worldgen, though.
All in all, thank you for your help. I will probably try scripting CoFHCore or tinkering with PFAA (since it apparently has all the materials you need for GT6 progression) next.
EDIT: PFAA works great. I might tinker around a bit more with CustomOreGen.