Not a moderator, but my opinion is that if your thread is another variation of some relatively common theme, and you post one or two pics with a request for more like that, then perhaps another thread isn't necessary.
You, on the other hand, have nearly 400 photos on one specific topic, which, although it could fit into other topics as well, is narrow enough that people who have such pics wouldn't doubt if they fitted into the thread.
I say go for the new thread, and share your treasures with us
