Well, I made it back to the yard today and took some pictures. I was wrong on the year, the Savana I saw was a 97. The 97 box mounts inboard of the frame rail, so if the box is turned 90* and tilted back to match the original box, the mount points will be on top.
I also saw a 93 van with a similar set-up. That box is mounted outboard of the frame, so when turned and tilted the mount points would be underneath. I think a bracket to mount that box would be easier to fabricate (2 plates welded at an angle and a brace would work).
I posted the pics on Webshots. Take a look and see what you think. One worry I have is the Pitman arms are very short, so the ratio with the longer AD pitman arm might be a problem.
Chev van power steering boxes