I'd think that the biggest question would be whether traveling through time would effectively sever Voldemort's ties to every Horcrux that isn't at Hogwarts. If it doesn't then he cannot be killed at all. If it does then they only have to destroy two, the Headmaster will have a strong suspicion as to the location of one, and they'll know that any remaining Horcruxes must have been hidden on Hogwarts property at the time of the transfer.
Of course, it would be interesting for the inhabitants of Hogwarts to visit the inhabitants of the Hogwarts native to the time. Could the portraits of any former Headmasters who'd been alive before the time period freely move between their portraits at both castles?
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"Anyone can be a winner if their definition of victory is flexible enough." - The DM of the Rings XXXV
Of course, it would be interesting for the inhabitants of Hogwarts to visit the inhabitants of the Hogwarts native to the time. Could the portraits of any former Headmasters who'd been alive before the time period freely move between their portraits at both castles?
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"Anyone can be a winner if their definition of victory is flexible enough." - The DM of the Rings XXXV