I'm thinking the wall you refer to is the one that slants in from the short side wall up and up to the ceiling? Not a normal vertical wall?
The magazine rack would probably work. I'd also consider a holder that you slide the rulers in from the side instead of the top as normally done. Perhaps mount the magazine rack at an angle. Maybe use hooks or a rail & hook system for the rulers that have holes (or drill holes in them) and let them hang freely. Or at least for the small rulers, so they don't smack you in the head.