Hey,
I am also working in Unity, and what I did is set the size of my camera to 72, and made the ratio of pixels to unity units 1, so that moving an object over 1 unit in the scene view will only move the sprite one pixel. That means that if the position of the sprite is an integer value, then the object will appear to be pixel perfect. Also, I was shown a script by Weegiebee: http://pastebin.com/typctTFd. Stick it on your main camera and set the height variable to 144 and it'll force your screen to mimic that resolution!
-Rad