^WotG is actually a very good idea and, just as importantly, very do-able.... for several reasons:
It is a fairly well known pop-culture title, even among those who are not hardcore fans of kaiju eiga.
Not being 'Godzilla' or any of his main stable of co-stars, I would imagine that obtaining the rights to the film from Toho would be comparatively cheap.
As I mentioned, star Russ Tamblyn is still with us and doing limited acting appearances. He is a likely candidate to join the cast, and it would be a bigger draw for fans and 'insiders' of genre stuff. He's embarrassingly acknowledged and apologized for how 'phoned-in' his acting was in the original, so this would be an opportunity to make amends for his less than stellar work in the original -regardless of how big or small his part might be - and would further immortalize him in the sci-fi genre lexicon.
WotG co-star Kumi Mizuno is likewise still around. Why not fly her to the U.S., or fly Tamblyn to Japan? Have them co-star as Paul & Akemi Stewart, married and long since retired. Whether the remake would acknowledge the original film or not it would be an outstanding fan service moment... and relatively inexpensive, comparatively speaking.
Legendary & WB pride themselves on 'star' power in their casts for these MonsterVerse films. Brad Pitt is a self-professed WotG fan, so why not ask him to sign on? He'd probably get a real kick out of it, and it would give the film a bankable name for that all-important B.O. $$$ draw.
For a composer they need look no further than Mark Mothersbaugh. He's a well-established composer in his own right and is a gushing fanboy of the original; (the encounter between him & Tamblyn many years ago is a classic anecdote). As such, I would be inclined to think he'd jump at the opportunity to get to score a big budget remake of WotG... whether adapting Ifukube's score outright, only a few selected cues, or a completely original score of his own. Furthermore, his band DEVO did a cover of
The Words Get Stuck in My Throat, so he could throw than into the soundtrack and we could torture yet another generation with that wonderfully awful song.
The total budget would be considerably lower than these more recent over-the-top CGI fests, because in addition to the cheap(er) rights acquisition costs, Legendary & WB should resist the temptation to overindulge in needless CGI and instead achieve the title creatures through practical make-up & prosthetics. Someone on the level of Rick Baker, Winston Studios, KNB or an equally prestigious F/X firm would be a perfect fit for revamped suits & make-ups for Sanda & Guira. Then, 2 stunt guys could just be turned loose in a huge soundstage filled with large rectangles of various sizes, everything painted green. Then the buildings & destruction debris could be CG'd in at a substantially cheaper cost (buildings would be much, much less expensive, I would imagine, than a pair of full-blown CG monsters).
The scale of the monsters could be kept far smaller than the current 300+ feet critters in the current roster of MonsterVerse beasties, making the action more intimate and the creatures a little more relatable.
They could make it full body horror driven film, like Cronenberg's Fly remake, or go the laugh & scream route, like
American Werewolf in London or
Tremors. It would work either way, although I would prefer something somewhere in between.
They could tie in the Frankenstein mythology as a throw back to FCtW... go the super-size Bigfoot route... play on stem cell therapy/genetic tampering gone awry... you name it.
The more I think about it, this would be a great fit for Legendary... with the potential to be a really wild & fun time at the movies and a big B.O. win in comparison the the initial capitol invested by the studios.