bet river, given his passive line on such a draw heavy board I'd be surprised if he had you beat. His most likely hands are pair+FD, and you're ahead of all of those unless he peeled Aw/Js/Qs and thats such a small part of his range.

Given his range is fairly weak, I'd bet ~$15 so he makes some crying call with 2nd/3rd pair. Also gives him a chance to randomly bluff raise with a missed draw.