[aargh57]

I think you gotta reraise here. Don't fear the straight or 66. I think you'll get called by 2 pair much more often than you'll get beat. If he wasn't a poster than maybe just calling would be better but here he could easily have K6, 86, 56, or even 26. Even if he's not posting reraising is probably correct unless he's very passive pf (or very tight pf as I don't see a tight pf player having anything (other than 65s) that you're beating when he calls).