try as hard as you can to get all of your chips into the pot. i push the river since you have like 1200 left behind. He might still call getting 2.5 to 1 or so on this. If he calls your all in 50% of the time, thats (1200*.50) 600 chips gained. He calls the small bet of 350 100% of the time for a gain of 350 chips.