I like the interlacing of the ghost house floor with the cave floor. It's done in such a way that it doesn't detract from the level quality, yet it adds a rather creepy atmosphere. I should probably add that I think the Fishin' Boo is one of the most annoying and unpredictable sprites in the game, but it seems like you've taken that into consideration with your design, so good work there.
Here's a demo patch for testing. I don't know if I should make it longer or not; right now it ends at the end of the fishing boo room. Too short? Too hard? Too easy? Feedback would be appreciated. There's a secret exit as well so keep a look out for it.