From the sounds of it you haven't actually found the intro text data, but the lookup table it uses to select characters. That's part of it, but not whole shebang. Chances are it's probably not compressed, but just different is all. I would set a read breakpoint for when one of the characters is used for the intro and/or do a trace log. You'll want to use Mednafen's debugger, it's the best tool for PCE hacking. She ain't much to look at, but she has a heart of gold. Everything's keyboard driven with no outward appearance, pretty much the complete opposite of FCEUX.