I am currently trying to do some voodoo with how to obtain ores in my pack, and I want vanilla nether quartz to not generate but to be obtainable. I want only for OSV nether quartz to generate, but I don't have a way how. Could you possibly add a config option to do so?

Are you sure this isn't working? It's supposed to do this automatically whenever netherrack variants of quartz exist. Although, looking at it again, it seems like I never actually updated it to support the multiple blockstates, so it might only affect the first blockstate of any block (ore_stone_variats:x_ore:0). If so, this is a pretty simple thing to fix and I'll definitely try to look at it soon. I've been super busy with classes, but I should definitely have a little time throughout the week for things like that. I'll let you know.

Sweet thanks. As a workaround, using COFH World seems to have the effect I need.

I believe this was fixed and not updated at some point, but it should definitely be working again in 5.0 due to block state flattening.