Keg,
The 787's are good on fuel, but there is no way 8T is ever going to be more than 120mins of fuel.
But, its good to see they can get there with 60 holding plus reserves if the have favourable winds.
in reality, the PER-LHR is not as fuel critical in the final stages as the LHR-PER will be. Lots of options in Europe, approaching PER, not so much. without a big tailwind, 8T won't get you to ADL