I'm guessing you're just planning on using blocks for the rear end, one thing I'd try is a guy named sid. He makes dropped straight axles for a living. Maybe give him a call and see if he'll make a raised axle. I've seen people do it before, it seems like you could bend it the other direction without much more difficulty and have a raised axle.
It's a long shot, but you never know!
Here's sid's website.
http://www.droppedaxles.com/