The unproduced film in question is this great 'what if' moment from Kaiju film history...Nessie!
When you put up the release of the 1954 Godzilla, I got thinking as maybe this could actually get made for a 1977-78 release and potentially have a interesting effect on British film industry as it might've saved Hammer Films as IIRC, this was a last ditch attempt to save themselves.
You can find more info on the film
here, but in short it was a co-production from Hammer and Toho to be released by Columbia Pictures and seeing these two studios working on such a film a an alleged $7 million budget would have been truly something. All it was that stopped the film was due to Columbia Films' president was caught forging cheques and that ultimately caused the film to fall apart. Perhaps one minor butterfly is another studio other than Columbia distributing the film and thus avoiding such a scandal.
IIRC too, had the film been made, Toho had the rights to trademark Nessie to join the Toho gallery of monsters and yes, it did mean Nessie would face Godzilla in some form. Who knows, maybe if the film was a success perhaps Hammer could start their own kaiju film series? Fascinating thought that though as a Scot, quite a proud thought to have a Nessie film that wouldn't be one of those silly B-movies we got of Loch Ness over the years.
Moving on topic regarding Alice, quite a very different film and I like quite the sound of it, though I do wonder if in retrospect for animation historians might see the 'modern' setting of 1969 at the start (and ending if it's just a dream?) look a little bit dated? Also it seems that with an
older Alice here that some forms of fanservice is at play here in the film such as the briefs shots in the rabbit hole scene, though how old is Alice here compared to the OTL 12 year old Alice? I get the feeling this version of Alice would be popular for, um, certain reasons...
Finally with your cast for Hansel and Gretel, I have these in mind to voice them.
Gene Hackman as Gunther/Farther
Maggie Blye as Olga/Stepmother
Bill Owen as Scuffler
Rikki Fulton as Toasty
Ian Lavender as Hardtuck
Haven't got anyone in mind for the witch unless you might have an idea, however I've added Scottish actor Rikki Fulton as I remember in the old American Magic TL how the birds were played by English actors (forget who though) that helped British humour find s footing thr states, maybe the same for Scottish humour with Fulton? Hope that all helps.