AKo Heads Up. What is standard?

[TTChamp]

Absolute 2/4 Heads Up

1st hand so villian is totally unknown.

Hero is SB (button) with A [img]/images/graemlins/diamond.gif[/img]K [img]/images/graemlins/club.gif[/img]

Pre flop: Hero Raises, BB calls.

Flop(Pot=4 SB)
J [img]/images/graemlins/diamond.gif[/img]2 [img]/images/graemlins/heart.gif[/img]3 [img]/images/graemlins/heart.gif[/img]
BB bets, Hero Raises, BB calls

Turn (Pot=4 BB)
7 [img]/images/graemlins/club.gif[/img]
BB checks, Hero bets, BB calls

River(Pot=6 BB)
8 [img]/images/graemlins/diamond.gif[/img]
BB checks, Hero checks

My main question is about my response to the flop donk. My normal response here is very player specific, but I felt like I should raise in this case because of the possibility he was betting a flush draw. If the flop came: J [img]/images/graemlins/diamond.gif[/img] 2 [img]/images/graemlins/heart.gif[/img]6 [img]/images/graemlins/club.gif[/img] I might just call and fold the turn, or raise the flop and check the turn and fold the river. My logic is that he is not donking on a drawless board unless he has a pair and most opponents at my limit won't fold any pair HU.

What is the standard flop play here against an unknown?