supermelon928

As others have said, the Greybeards shouldn't be involved, lore-wise. Neloth would indeed be a better choice. Also, traveling back in time with the Wooden Mask would be another good path, but it would add the task of expanding Bromjunaar Sanctuary and/or creating a cell of new content. On the other hand, if you use Bromjunaar and add your own past dragon priest, you could have it voiced, while Arngeir and Neloth would have to silently communicate the new dialogue.

Maybe on the edge, against the outer wall.