Just to clarify a bit, 2" of actual lift height is generally the max you can go and still be able to align it.
A 2" thick spacer however will lift the truck 3" due to the lever action of the TTB suspension, and it may not align correctly.
IIRC, the F-150 pieces are 1.25" thick and give just under 2" of actual lift (a 1" thick spacer would give you 1.5" lift).