You did fine. Tons of guys are running that spacer.
the reason for the 3" block is to gain a small height increase. It is not actually a 3" lift, it replaces the factory 1.25" block resulting in about 1.75" lift.
This allows the guys that install a 2.5" lift in front to gain clearance and still have a little bit of rake.
If you do not want to fuss with the back, a 1.5" leaves a tiny bit of rake, the 2.0" gets you pretty level, and the 2.5 is slightly over level.