MNF 2 in HS 1, it won't work at all in any other engine because it won't be the same game. It simply won't be. Everyone has their own cute charm in HS 1, and most people fell in love with the game because of the story and characters (models, graphics) and it's surroundings. Sure there where not so many places they went, but that's probably because you started to divert off into my new memories.
I remember in a post you where deliberating which engine to use, then you said your where just going to stick with hs1 etc.
Your last update you hinted at suddenly wanting to use HS 2, despite it significant failings compared to HS 1. Most of us know what those failings are in HS 2. Tupee s for the men, graphic clipping , looks like everyone took a bath in oil, horrible glow. animations glitch like crazy, and you constantly get animation clipping, where one animated area protrudes through another , not something you can fix or avoid if you want animation. Your limited to what you can really do to the characters, in other words the characters from HS 1 are not reproducible, in HS 2. They are unique to the engine, just like the glow dolls and men wearing tupee's and animation clipping which can't be fixed. Not even sure why shitty HS 2 even exists, it's like using windows 98 (HS 2) v windows 10 (HS 1 despite this being much older than HS 2!, it's night and day.)
I hope and pray you will stay to your word and continue MNF 2 in HS 1 just like a lot of your fans want too, because it would never ever be MNF, just something using it's name. Spin offs rarely work, especially if you significantly change things.
You know what your doing in HS 1 we love it, so make it MNF 2 in HS 1 too, from a lot of your fans!