Somewhere on my list of projects is "Gut a 12" Powerbook and put the guts of a modern M series Macbook in it". The chassis is so spacious and the Macbook Air logic boards are so small, physics is not going to be a problem. Just hooking up screens, the keyboard and trackpad (using the original, natch), and ports. There's already a high-res display swap you can do in that chassis to get to 1400x1050.