Taylor, playing his 150th one-day international, finished 102 not out with a boundary off the last ball, while Williamson top-scored with 112.
     
Opener Martin Guptill also contributed 76 to help set Pakistan a mammoth target in the second and final match of the series.
     
It was New Zealand's highest ODI score against Pakistan, beating the 311 made in Auckland in 2011.
     
The total was the Black Caps' fifth highest in one-day history, surpassed only by scores against second-tier nations Zimbabwe and Canada.
     
Pakistan's batsmen will need to fire to avoid a series loss after the tourists slumped to a seven-wicket defeat in the first match last Saturday.
    
 More importantly, the huge total will raise serious concerns about Pakistan's attack with the World Cup set to begin on February 14.
     
Mohammad Irfan was the only bowler to look remotely threatening, finishing with two for 52.
     
Bilawal Bhatti was carted all over the park, conceding 93 runs without taking a wicket in his 10 overs, while Ehsan Adil fared little better, taking one wicket but going for 8.5 an over.
     
New Zealand skipper Brendon McCullum started with typical aggression as he plundered four boundaries from Bhatti's first two overs, including a six over the bowler's head.
     
He should have been stumped two overs later charging down the wicket to a Shahid Afridi delivery, but keeper Sarfaz Ahmed was daydreaming and missed the chance.

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