Doing some additional work on my son's pickup after I had a mechanic replace the evaporator. Time to replace the shocks. It appears the previous owner installed Bilstein 5100s on the front in an attempt to level the pickup. I'd like to add 1" blocks on the rear to give it a tiny bit of rake. I assume I will need to buy the Bilstein 5100s for the back end that are made specifically for a 0-1" lift? Additionally, is an alignment recommended after lifting the back end 1" and simply replacing the existing 5100s on the front end with the same shocks?

Technically, by (re)introducing the rake, you are affecting the caster, not by much though. Do the work and see how it drives. It may not be necessary, but I always get an alignment after I do suspension work. I like the peace of mind.