ZDoom

Can someone please help out with making the brain on this spooder (Insane Spider from Bosses.wad) darker gray + 3rd eye like in Demolisher, also Arachnorb Queen's mouth?
Link to full frameset: https://www.dropbox.com/s/oi5rvrkd1mqxa ... r.zip?dl=0

Example:

Spoiler:

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You might need to clean up parts of it.