Bet how much on flop?

[tewall]

Here's a situation I've been thinking about. Say the blinds are 25/50, and you and the Big Blind have 750. Only he calls your PF raise of 150. You don't have any reads on him, and your image is tight. The flop misses you, and he checks. So the pot has 325 and both you and he have 600 left. What do you do?

It seems to me either going all-in or betting a half pot are reasonable plays. Are there reasons to prefer one over the other? Do your cards and the flop change your decision? (remembering that the flop missed you)