You can shim it up to the limits of the steering caster angle:
- http://www.4crawler.com/4x4/ForSale/Shims.shtml#FAQ1

I run rears up front, with about a 1" longer-than-front-hanger-drop front shackle, high pinion 3rd and no shims:
- http://www.4crawler.com/4x4/4R_suspension-III.shtml#Front
Works fine.