@NC-RetiredI don't consider a classic do-over or time loop scenarios time travel, but only information transfer. Therefore there's no dichotomy between the younger and older "self" it's just a download of an update.
It's most consistent with the simulation hypothesis. A snapshot is made, then the simulation (or derivative) processes for a while until is terminated, or not. Another derivative is launched from that earlier snapshot, but with updated memories of a single (or more) characters from a later snapshot. Them being dead, perhaps long dead at that time isn't a complication if the last state had been saved. It places a lot of implied importance on that character, unless it's a random glitch in the system or common practice to run uncountable copies of the simulation with all kinds of subtle changes (multiverse).
Subjective, the youngster just wake up one day having dreamt a version of the rest of their life overnight. The "dream" been so vivid, they may have trouble to get back up to speed with current events (older displaced the young), or not so much (older "taking a ride along").
If it's full replacement, the old mind in young body would probably believe they're on a do-over with no much additional convincing needed. If the younger mind is left intact, just updated with a bank of memories from the "future," it's way easier to ignore those just a freakish vision. Precognition value of that vision would be very important then, and should be established quickly, before the memory of it fades. The key of retaining memories is to revisit them.
Unfortunately, our memories aren't exactly reliable, each such recall introduce subtle changes to the memory itself, as it is being reinterpreted in light of current context and purpose of recal. People easily and seamlessly retcon current, changing, political beliefs or stances upon their memories for instance, seeking to keep their personalities and character more consistent than it is. Unless, the change is a key element of the memory, but then the perceived motivations can be adjusted or explained in a new way. Even facts drift easily. Complex, chaotic events are over time polished into easy to tell legends that aim to retain and crystallize the overall impact at the expense of seemingly irrelevant details. What details are seen as irrelevant may and will change over time. To refill lost details comparing notes, by fact checking or talking with others who were present is important. Curiously, with right nudging, the latter may introduce completely new content that's wholly fictional into the memory, still strongly believed to be factual afterwards. And neither is available for future memories of our do-over character unless they meet someone else who's likewise updated.
There's no warranty the implanted memories, as retained in late life will have relevance or even resemblance to the young persons current events even if the world itself would experience no random change. With I find extremely unlikely. Lottery ticket numbers, basketball or even soccer game results to be exactly the same, I don't believe it's possible. General trends may hold, who made the playoffs, even the champions may still be same, but it's not a given.
Those changes of the underlying world will quickly accumulate. Not to mention, by making any different choices in their life, something that's almost inevitable regardless of "future" memories, the character would experience the world differently, visiting different places at different times, participating in different events.
Unless cherished and cultivated, the relevance of the "visionary dream" will diminish quickly, eventually reduced to just a strong "hunch" how the world events would likely unfold. Not very different from just a strong intuition, and likewise not always right either.
While in personal life there could be strong impact early on, it too will fast lose direct resemblance of the vision. Resulting in it to be increasingly dismissed as misleading. Paradoxically, the faster the more impactful it actually was.
However, yes, I would take the chance, would it be on offer. But I wouldn't dare to go before 1992, just for paranoia; the "song revolution" could turn into bloodshed far too easily. Sure, there's a few personal memories and experiences I would like to revisit before then.
But well, I turned fourteen in 1992 so there's that too. And there's hope to find those memories fresh. I would rather go for just visionary fact dump than a full personality rewrite, believing (likely falsely) that I haven't changed all that much and would know how to handle such a vision even though some of the most vivid highlights could be very confusing.
