Tip: You can use Lunar Magic's Overworld Layer 3 Editing system to edit or create your own layer 3 images (castle bricks, fish, rocks) and apply unique effects per level via the Layer 3 Bypass in the main editor.
Well, I made some changes on the shading of spiny, since it was too dark. Lakitu has some nice shading, tho. Nice job. As a suggestion for a future update, I'm curious if you could change the cloud sprite of Lakitu to look better, but by looking at GFX00, I think it would be too hard, so, well, it's already good as it is.
I've also accidentally included smw bob-omb that looks like the one in SMB3 and percentN's pipe for the growing/shrinking pipe sprite. But you can use them if you want to. Oh and for the pipe, I've copied the foreground pipe and recolored it.