Well, I haven't posted in nine months, but seeing Filler talk about a Famicom game from 1987 woke me up...
I had a look at this, just to see what work would be involved in getting it done. There's not a huge amount of text to go in there, and it reminds me of when we worked on Sherlock Holmes over two years ago. That game, like this one, was an MMC1 mapper game, 128KB in size, and I switched that to an UNROM mapper with 256KB, making it trivial to fit all the dialogue in. Comparing this script to that one, this is even smaller, so getting the text in there shouldn't be a problem.
I analysed the text routine, and it doesn't seem too big of a deal: the game just looks at each character in turn, assembles it in RAM and then plops it in VRAM once the line is done. It dedicates two lines to each one because of furigana, but that could be modified so that every line of the text block is used, giving you a 20x8 window - that could produce side effects that need to be addressed, though.
Of course, I just looked at the first dialogue box in the game, so there might be other bits of the game that are more problematic. And I haven't looked into the title screen, and NES title screens are harder than they look due to the tiny amount of space given to them. FlashPV does great title screens but actually getting them in there can be a tricky process, sometimes needing modification. As such, I do NOT want to promise anything at all.
I'm not even sure if I can do this owing to time, and I hate to let people down (I have let you down before, alas). I just wanted to give my thoughts after a brief analysis, and suggest that I MIGHT get further into it, time permitting.
Don't want to give false hope, but if I have a few days free... it's possible.