Best case scenario Luciferio wins, worst case this ends in a stalemate.
A lot of the arguments presented for Zeref doesn't seem to use in character despite the amount of time (lol) he should've theoretically had to do any of the things being debated. So the whole: "hurr durr tiem staph deff machic" argument kinda falls flat, unless you literally ignore every encounter he's had in the story. Which I mean, all power to you I guess? But given the source material has shown he directly doesn't result to this, I think it's safe to say the match isn't won nor operating under the ideal that this occurs. Have a problem with this take? Take it up with the author, it's not my fault he made his character use his move set in midly incompetent fashion and this isn't a plug and play moment where you're putting a controller up his ass and using his skill set as you wish he would.
But in the off chance someone still brings this up for whatever reason. (I know it will be). Then I'll ask for the mechanics of how the Death Manipulation operates. Does it apply the concept of death? Does it life drain? If so, how fast? Does it stop bodily functions? If so, which ones? Like what does it actually do to kill and can it be proved by a consistent basis presented within the series? And lastly I'll ask how that method you provide interacts with the unique physiology of Devil's. But regardless of this, the forbidden Magic of Devil's are shown and outright stated to interact with intangible concepts (Lilith & Naamah, Luciferio Ehanced Morris for a more 1 to 1 comparison), so I'm not quite sure why this wouldn't apply to Luciferio's passive presence thats directly stated and shown to restrict the effects of magic, bar the antithesis to the entirety of the verse, Asta & Liebe's Anti-Magic.
Best case scenario as stated above is that Luciferio's passive presence or more active/offensive use of it would allow him to restrict Zeref's magic effects. That would include his death magic, time magic (seeing as he scales above the Devil of time anyway) and any other effect he's shown at his disposal. Probably operating on the same basis as Natsu burning his form by directly affecting his magic.
Worst case scenario is neither can kill each other. With Luciferio being faster by a significant degree and having not only POTDK passively restricting magic effects, but Devil's in general being pretty resistant to magic and Zeref being able to constantly reset himself to a previous state. Though I guess depending on the incap requirement here, that's also a possible winning condition for Luciferio.