Can you win this sectional Swiss?

It's the final (7th) match of the Central Massachusetts sectional.  There are 26 teams, and your team is atop the standings by 2 VPs and is playing the 2nd placed team.  The match is going fairly well through the first seven boards.  They've just bid and made a vulnerable slam but you're fairly confident that your teammates will have found it too.  In actual fact, it turns out that we are up by 9 imps at this point and, again in retrospect, we can lose as many as 4 imps on the last board and still win the event.  You pick up this collection in third seat (we are vulnerable, they are not): ♠K8 ♥864 ♦AJT75 ♣AQ8.  Your RHO, somewhat surprisingly opens a weak 2♦.  Things are looking good.  With our side silent, the auction proceeds: 2♦ – 2♠ (forcing) – 3♣ – 3♥ – 3♠ – 4♠.  Partner leads ♣7 and this dummy appears: ♠T2 ♥5 ♦KQ9842 ♣KJT9.  It's possible, by the way, that some of the spots are incorrect.  You win dummy's low club with your Q and it's over to you.

Many of the other teams have finished by now and the noise level is right up.  People are picking up bidding boxes, folding tables, and so on.  It's not the best time to be analyzing the hand.  I reasoned as follows: dummy won't be providing any tricks for declarer unless it's a heart ruff, so unless declarer has 10 running tricks in his own hand, in which case no defense will matter, it can't hurt to shift to the SK.  After all, if declarer wants to finesse against my K, he can presumably ruff a heart and run the T.

How do you like my plan?  It turns out my analysis was superficial.  This was declarer's hand: ♠AJ973 ♥AKQT32 ♦– ♣62.  Strange as it may seem, there's only one card in my hand that it's safe to play: ♣A.  Oh, and by the way, if I do correctly cash out then lead a red card, and if declarer does ruff a heart in order to run the T, not only must I not cover, but partner must hold up his Q!  Ultimately, his six will become the setting trick!  The whole hand hinges on the relative weakness of declarer's trumps and his transportation problems.  He can't ruff a heart, finesse in spades and get back to his hand to draw trumps without losing control. 

Our teammates were in 4♥ at the other table which has no prayer as it turns out, despite the robust trumps, since declarer is permanently cut off from the dummy.  So, we lost 11 imps on the board and ended up tied (with our last opponents) for 2nd place.

We had a great day, though, and all my teammates played really well.  Thanks to you all.