I have the Teraflex 2" BB..... here is my install in under 2 hours.
The isolators on the back are much thinner than the front... its up to you on what you decide.... I kept mine in and sat pretty level.
Are you sure the spacers are different lengths? Mine were 2" for all four... the bump stop extenders are different front to back and must be installed as per the directions to give proper bumpstop operation.
My part number from Summit Racing is TeraFlex 1341200 - TeraFlex Suspension Budget Boost Coil Spring Spacers
FYI... if you have vibes after the lift... I did... you can fix it in two ways.... t-case drop or 1" MML. Let me know if you need anything... I can give you some insight ( as many otheres can as well )