The stalwarts and teammate Dylan Moore were superb in Hawthorn's 13.9 (87) to 7.7 (49) victory in atrocious conditions on Saturday at Launceston's UTAS Stadium.
Moore was best-afield with 32 disposals, two goals and nine tackles as the Hawks climbed from seventh to fourth ahead of other results.
But the 11th-placed Power slipped from finals contention - they'll likely be four wins outside the top eight with five games remaining.
Port joined a succession of clubs unable to control Hawthorn's 33-year-old stalwart Gunston, who has now kicked 42 goals this season.
And ex-Port utility Impey put the finishing touches with three goals in a 10-minute burst in the final term.
Port kicked with a gale in the opening quarter, but the Hawks were superb - after a feisty start, scores were locked at 3.2 apiece at the first break.
Hawthorn's Calsher Dear booted the first goal after Port's Ollie Lord was penalised for a behind-play bump on Hawk captain James Sicily.
The Power responded with a Mitch Georgiades goal 18 seconds later and, while Port celebrated, Sicily slung Jack Lukosius to the ground, resulting in a free kick.
Lukosius converted, but the Hawks then generally held sway into the stiff wind, with Dear's late second major levelling scores.
Hawthorn then cashed in with three goals to one in a rain-soaked second stanza, with Gunston booting two, including a stunning 30m set shot from a boundary line.
That strike gave the Hawks a handy 13-point halftime buffer, 6.4 to 4.3, but the lead rapidly disappeared in the third quarter.
Port's Jordon Sweet and Lord goaled with set shots to tie scores, and a tense seven-minute stalemate followed.
But the Hawks, against the tide, then made a decisive break, with goals from the influential Moore and Gunston creating a 12-point advantage at three-quarter time, 8.6 to 6.6.
Hawthorn then swept to victory with five goals to one in the final quarter.
Hawk on-ballers James Worpel (26 disposals) and Josh Ward (26), Impey (26) and Blake Hardwick (27) revelled on the heavy track.
Port's Lukosius and Georgiades scored two goals each, while winger Jase Burgoyne (26 touches) and half-back Kane Farrell (25) were busy.Â
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