That would make the FuSoYa character entirely pointless, though. If anything, ditch Rosa or Rydia there, you don't need three mages. Then again, you don't really need Cid there, either. Losing characters in the original was so annoying; I hated that they took Kain away for FuSoYa, only to give him back after one dungeon, and reset his equipment. That bastard ran off with my Avenger one time when I forgot to take it off! Expanding on that even more, by taking FuSoYa away mere minutes after getting him would be really dumb.
Obviously ROM hacks can do whatever they please, but the more practical thing to do in the original game, without having to force another party change or removing FuSoYa as a playable character, would be to throw some mechs into the Tower of Zot.