If Brooks can't help you out I can but just know it will take something special in trade as nice Cocobolo Burl is rare as hens teeth & I only have a few pieces left in my hoard. I would also sell depending on what size piece you need.
Your message folder is full. Note there are a couple spots shy of 3/4" because of how the burl was formed. I was willing to send either the 8" or 6" piece & throw in the 4" piece in case there was any issue. You should be able to get 2 pieces from either blank to make the pen you are working on.