How do you calculate shock size and strength needed?

Hey Max I tried searching this before I posted but I kept finding pages of info where everyone but you had commented on shocks. If you've already answered this feel free to post a link and just close this out.
 
How do you calculate how much stroke/compression you need with shocks? What about adjustable shocks? Any brands you recommended? I've read that you don't want your shock being your limiting factor on lift/drop. Any other suggestions? One of my trucks is setup bag on bars and the other bag over axle. Do I need a different type of shock for different rear designs?

 
Thanks ahead of time

It's in the chapter on shocks, in Max's book.  No wait Max hasn't wrote the book yet.

Call steve at RCD and he can get you in the right direction.  Theres an add for him at the top of this page.