Fun hack there mate, I enjoyed it.
Some feedback here:
-Try to avoid "fillers", like some random shelljump, or jumping from enemy to enemy like 5 times. It's not a big deal tho.
-Try to put a launcher here, seems weird having the generator withouth its sprite. Same happens in one of the ghost houses.
-When you start this level, you can't see Toad coming down this pipe. I don't why, maybe priority?
-Try to patch L-R (screen scroll) if it is not used. You usually can respawn enemies/shells and make some sections easier.
Truste me, I know about this kazoo stuff