I think shackles are available in 1.5 and 2" lifts. The mfg. should list what lift they are for on the product information.
The spring will have a tendancy to spring up not down. A leaf spring's resting state is fully curved (up), loading a leaf spring makes it flat (down). Put jack stands unter the forward leaf bracket and rest the differential on the jack. the weight of the axle is where all the force comes from once the shackels are off. the springs will flex upward if there is any remaining tension on them. Depending on what shape your springs are in, you may have to pry them down to get the pins out as I did. This is where a second light duty bottle jack is nice, but not a nessecity. It allows you to control the spring very precicely.

Also, stock shocks will work with a PML but longer can be used if you plan on getting a full lift later.

I just remembered, be sure your lift is even from left to right or it may give you issues when it comes time to do the alignment.