I didn't know that Greg had already implemented this, but it's glorious.
Re-enable GregTech. Create a new world. Now ores spawn together with other ores (like IRL) in mixtures, so there will be clumps of iron, copper, chalcopyrite and pyrite spawning together at y10-40.
Remember that Lignite also contains coal. I think.
You can see the Resurrection ore configs here: https://docs.google....wHi_jg/htmlview
I'm not entirely sure if you are right about that considering that Gregtech is set in it's config files to disable all vanilla ores, its config file is set to: B:DisableVanillaOres=true. Since that is the case no vanilla ores will spawn. Even so after disabling the mod and making a new map I still couldn't find tin, copper, iron, or coal. I don't want Gregtech, it needlessly over complicates things to the point that I don't take any joy out of the game, it's more like a chore to play.
So yes, is there any insight as to why vanilla ores are not spawning even with Gregtech turned off and that it is a new world?