Kudos for the idea of puting the lid on the inside of the box! It'll look better that way when you have more of them in a row or stacked.
On the grapic design subject. I suppose you've created the box in some kind of 3D CAD program, and if you're not using an old version it's easy to just drag in a picture (perhaps found here: http://www.boardgamegeek.com/article/16861446#16861446) rezise it, trim, print, cut and glue.
Good luck! Looking forward to see the progress on you project