My main concern is that there doesn't really appear to be much 5e support for Modern character options. Could we convert yet retain the essential flavor of "Cyril" et al? I'm not sure. Your characters are all wonderful and I'm hesitant to mess with that.
On my end, converting monsters from 3.x to 5e is, admittedly, tricky. I tried to re-work a bunch of 3.5 Planescape traps and monsters this past spring, and it was no fun at all. It's apparently a heck of a lot simpler to convert 1e monsters to 5e than it is 3.x (not that I've tried, at least not yet).
The adventure I'm running for you here, however, is a module that I'm only loosely following. I chose two real-life news stories and am layering them on top of a 3.0 d20 Modern module. What I would do is just pick up my 5e MM and select substitutions for any of the pre-statted monsters and NPCs that I've chosen to retain from the module. The thrall, for example, is 30 percent from the Scarred Lands Creature Collection and 70 homebrew; I basically already statted it out by hand, so in that sense it's no more work to pull something from the 5e MM and/or re-skin a monster than what I'm already doing.
The PCs are the main thing. I don't know that the characters convert easily. And I don't know how well Wizards will support Modern under the 5e rubric...my guess is not that well since their focus appears to be on adventures and on The Realms.