It's absurd that they aren't bulldozing Fear Factor right now. Everyone in real life that I have mentioned the Ministry idea to loves it, Hagrid is proving that people are still hungry for Potter immersion, it is the last iconic theme park ready land in the series, this should be happening yesterday.
You make it all indoors, connected to the rest of the London facade, build it like EPCoT's Land pavilion, multi-story with the golden fountain in the center, with a Ministry Employee canteen themed quick service restaurant where you can glimpse animatronic House Elves cooking on the ground floor.
It should have three attractions, a big exciting e-ticket themed to the Department of Mysteries, a show based around Death Eater trials, and a dark ride telling a Ministry Approved Wizarding World History as an example of the dangerous powers of propaganda that Rowling made a point of highlighting in the books.
It is a perfectly set up location to make use of any and all actors who still want to (and are able to) be involved, without the exclusions of those who do not (or can not) wouldn't seem weird/obvious. So while I and many others would go crazy at having say Imelda Staunton back as Umbridge if she wasn't there it wouldn't seem odd because there is plenty you could do in the Ministry that she wouldn't be involved with.
It is a slam dunk idea and I am nervous that they haven't pulled the trigger because of Fantastic Worlds. No one really wants a Fantastic Beasts ride much less an entire land, building the British Ministry unconnected to your Wizarding London land is dumb, building a different countries Ministry is stupid and building The Ministry but set long before anything you cared about happened there is ridiculous.
Have confidence in your abilities Universal, build The Ministry in the Fear Factor spot now, and build a great new park with zero Wizarding World stuff (at least until WB figures out how to make new films set in this world that actually connect with audiences) I know you can do it Universal.