I'll release the hack tomorrow, guys, everything seems to be finished and I've fixed the bugs that I wanted to fix.
The hack is confirmed to work on pc emulators fceux, nintendulator, nestopia and punes. Also on wii emulator fceux. And also on hardware everdrive on a real NES.
I've managed to redo the ending properly. Won't post screenshots here though.

The zip will include both english and portuguese versions. Just choose which ips to use when patching.
I'll submit the hack today here at RHDN, but since it is a delayed process, please go to my site to get it in the mean time (tomorrow!).
Also, look what arrived in the mail just in time:

If I scan the whole manual
would someone please do a full literal translation to english? I couldn't find the manual anywhere on the net, even on japanese sites, which is why I bought this. I know a bit of japanese, but someone who's really fluent could translate it much faster and more accurately.
As you can see on the famicom version's back boxart, it seems like the darkworld enemies are undead with long sleeves, as I've always pictured them:

The manual calls them "underground people gaia" and "underground people gnome" though.
So, some of you won't like it, but I've changed them one last time. Opinion was diverse anyway, so I went with what I felt that worked: I've reinserted the richer animation and I've changed the masked man to a zombie type to avoid any confusion with gnomes.