[Destroyman]

Okay, I would adapt Kamen Rider Kabuto as a new Beetle Borgs series. It'd be called "Beetleborgs Zect". The reason being that since the last two KR adaptions have been low in ratings & popularity, calling it Beetleborgs could potentially bring in fans of the original show. I would also try my best to give the show some depth & maturity to keep said fans interested but not go so far as to lose the kiddies.

The plot itself would be similar to Kabuto's, where an insect-like alien race with the ability to shape-shift has infiltrated our society & is secretly trying to overthrow humanity. And the only organisation capable of stopping them is ZECT, with their state of the art "Zecter System".
Now, in my version here there wouldn't be anything like the Shibuya meteorite, & the worm definitely wouldn't kill as many people, also ZECT would be a whole lot less shady & more like MIB.
I'm not going to go into huge detail about the characters, but I'd keep the Tendou-Kagami relationship mostly the same, where you have the inexperienced rookie being taught in indirect & strange ways throughout the series to follow his own path & do what he thinks is right by a jerkass who happens to be an essential part in defeating the alien threat.
As for the other riders, for the most part I'd have them all on the same side, but with some, less-than-perfect personality traits.

As for actors, I don't know, whoever does well in casting. And for footage, well since they're largely on the same side I'd cut the stuff with the Riders fighting each other, I'd want to shoot a scene where the 5 main Riders (Kabuto, TheBee, Drake, Sasword & Gatack) are on screen at once, fighting a common enemy (which never happened in Kabuto) & I'd want to shoot an episode with the Movie Riders where it's a future episode where the worm won & they're the resistance.