I designed my own characters and made my own game one long time ago... let's see if I can find the sprites I made.

ah I found them... I called the game FF animals

Fighter was a Trainer, and upgraded into a Master
Black Belt was a Lizard, and upgraded to Chameleon(using the color changing palette, it was tight)
Theif was a Tiger and upgraded to a Lion
Red Mage was a Man, and upgraded into God (could learn more magic in my game)
White mage was a Falconess, and upgraded into a Phoenix
Black Mage was a "Unknown" and upgraded into a Dragon

I think it was pretty tight. Completely overhauled world map and everything. New town sprites and such, stackable mountains that are walkable on in some places. At least, that was my really good hacked game I never distributed. Yeah good times.

the main site with FFHackster has all sorts of hacks, one prolly has the FFIII sprite overhaul

THE JACKEL