You don't have to 'pick' an interpretation for the Ace. If you hit A6 and draw a 3, you should stand against any dealer upcard, since you have a twenty.
If you hit A6 and draw another Ace for 8/18, what you do should depend on the dealer upcard. For example, against a 9 you would hit again, but against a dealer 2 you would stand.
Have I understood your question appropriately?