[APXG]

The way I see it there are 2 options: a)bet turn like you did, I'd actually make it 500-550 to erase any hope of fold equity or some other fancyplay OR b)check turn and fire all rivers when checked to.

A straightforward opponent is unlikely to be bluffing the river after missing a 2nd barrel, so either he is checking the turn with the intention of getting it in either through turn crai or a river bet, or he's just giving up.

Thus -- the standard line in your spot would be betting the turn, but if you have "added info" that he is straightforward and won't do anything tricky in a fairly unattractive river bluff spot(and want to trust this read), you can express the observation by giving yourself a free card and saving thereby 400-500 turn bet.

He is folding the turn like 80% of the time anyway, so the truly bad play would be check turn, check behind river -- anything else is fine. Actually, the edge from taking the tricky route is gonna be so small that it may not even be worth bothering with.