Basic suspension lift question (89 Burb V2500)

[Electricduane]

A "suspension lift" usually involves larger leaf springs and a block that goes in between the axle and the leaf spring. So what people call a "4 inch lift kit" amounts to larger leaf springs and a block that, when installed, add approximately 4" of additional height to the rig. CORRECT?

On the other hand, a "shackle flip" kit actually replaces the rear spring shackle with a new unit that reverses (flips) it. The end result of a "shackle flip" is an increase of overall height of the rig, usually in the range of 4". CORRECT?

A "shackle flip" is considered superior to the usual "4 inch lift kit" (larger springs and blocks) because it involves greater stability/flex and overall sturdier construction and better handling. CORRECT?

Reason I'm asking: my 89 Burb 2500 (3/4 ton) has a block lift. I think it is a 4" lift, but when put on a 3/4 ton truck, the end result is probably more like 6". It frankly is a bit more than I want/need, as far as overall height and driveability.

SO: what happens if I get rid of the blocks and put on a shackle flip? What do I need to do to be sure that the rear axle ends up at the same height as the front axle?

Sorry for the "noob" questions and thanks for all input.