[Alchemist]

I think calling 3rd behind an Ace who completed with your 766 is dubious at best.

On 5th you want to bet to see where you stand. You don't want to give him a free card if he is going high with split Aces. If he calls, bet into him again if he bricks 6th. You also want to put pressure on him if he's only got 4 to a low right now. Since he completed 3rd, is showing A68, and lots of Sevens are dead you don't have to worry too much about him backing into a straight.