All in call is fine. (I think you know that.)

It's really hard to determine which play is correct preflop deep stacked in basically any situation. Usually AK is a hand that you should play super-aggro preflop, but this is a very extreme situation. I think the two most reasonable plays are limp and overbet push (A normal raise risks a whiffed flop with an awkward stack size OOP, possibly against many opponents.). The EV of limping is really hard to calculate, but if you can put the table on rough limping ranges and calling ranges, the EV of pushing's not too hard to guess. Unless this is an oddly loose/passive table, the EV of pushing is probably pretty close to the size of the pot, and I can't imagine that the EV of limping is that good.