Essentially, I'm not sure "where" stored Portent rolls "exist" while not in use.
The simulacrum spell description says:
It appears to be the same as the original, but it has half the creature's hit point maximum and is formed without any equipment. Otherwise, the illusion uses all the statistics of the creature it duplicates, except that it is a construct.
When you finish a long rest, roll two d20s and record the numbers rolled. You can replace any attack roll, saving throw, or ability check made by you or a creature that you can see with one of these foretelling rolls. You must choose to do so before the roll, and you can replace a roll in this way only once per turn.
Each foretelling roll can be used only once. When you finish a long rest, you lose any unused foretelling rolls.
Presumably, if you used Simulacrum on a creature with the Lucky feat, the resulting simulacrum would be created with Luck points (the same number that the original creature had at the time of casting). Does Simulacrum interact with Portent in the same way?