3b/f turn or just call?

Just call, imo. Tightest possible config. You block many of his natural bluffs making his range a little stronger and more polar(?). Collecting an extra bet from worse than Kx rather than forcing them to fold turn. Consider kr river blank if you sense this turn raise is thin.

The flop CR is standard. It's a slightly wet board and you don't want him checking back the turn if a spade or any perceived scare card hits. Also, I think it's more likely you get paid off with some of his worst hands. If you CR the turn he might fold QQ's or JJ's.

I would just call the turn raise although I think it is close. You block AK. Does he have KQ or KJ in his 3 bet range? If he does bombs away but based on my definition of nit he does not. I have saved a ton of money throughout the years playing carefully against "Nits". Also, if he could have a slow played TT's or even 77's it becomes a very easy just call. Another argument for just calling the turn is that you would give yourself the chance to suck out with an Ace whereas 3b/f you would not.

What is your definition of "nit"? I've been called a nit but I can have 77's and KQ or KJs here or worse.

Seems good so far and just call down

Life becomes miserable if you three bet the turn and he raises. Is he overplaying AK or does he have a set? I’m not good enough to fold at any point in this hand so I would just call down. If he checks the river you were duped.

When ranges are wider preflop, you can and should 3bet this turn. But as Munga noted, this is literally the narrowest range situation possible, you block AK, and it's not clear that a guy like this is going to raise all of his Kx combos on the turn. I'd just call and call pretty much every river. If you do end up winning, make a note, particularly if this ends up being a bluff or some weird FSDR-type play.