I would like to offer my perspective on this as I think that most people in this thread are greatly undervaluing how big a hand HU AK is. I would ship AK in preflop HU for just about any amount of money. If you are playing super low stakes, it is possible that you may not want to get all of the money in if you are 200bb deep or more, but I would say if you are under 200bb deep, get all of the money in preflop if necessary at any limit.
If you are playing higher stakes, then it is even more of a no brainer no matter how deep you are. Because once you are deep, people will 4 and 5 bet you really lightly preflop and you can have fold
equity shipping the money in postflop. So it depends a lot on the ebb and flow of the HU match, but I am usually inclined to play for stacks 300 + bb deep preflop with AK.
If you are 100bb deep, it is really not even close. You should be doing a Tiger Woods fistpump if your opponent is willing to get the money in preflop when you have AK.