Here are some images of what I had in mind. Please reference these to see what would look best wherever:
Images:
Replacement NPCs/Blocks etc:
Blocks: Doesn't really matter to me, I guess it'd work to replace the SMB3 grass or SMW grass.
For the krocheads: block-55
NPCS:
For the cattails: NPC-226, 213, and 214 (do whatever to the top of the cattail with you judgement)
Background: background2-13 or background2-20
Background Objects: Again your call there, I trust you know what would be good to replace any background objects like tall grass, dirty swamp water, lily pads, etc, etc
Other Information:
File must be uploaded to Mediafire because that works best with my computer.
I know this is a lot of stuff, but I need all of it for the level(s) I plan on using them for, and it'd be very annoying making separate posts for each tile, npc, etc, so if anyone can do this, I'd greatly appreciate it!
Thanks again on whoever is willing to do this. It means a lot!