Pinion Angle Change?

Whats an acceptable amount of pinion angle change for a 4 link on the rear of a truck from full up to full down?  I know zero would be the best but just curious if there is some wiggle room. 

 
Thanks...

I've never really figured out mow much change is acceptable, but I can tell you that if you follow my suggestions for IC placement and don't try to run 24" of travel, you shouldn't ever have any pinion issues.   Someone else might have the answer to this one.