S/S Spring Lowering Blocks?

Thinking of putting S/S Springs on my 68 Satellite and I noticed Mancini sells lowering blocks to lower the body back down after installation of the springs...any guesses as to what thickness to buy to get close to normal rear ride height? They offer them in thicknesses of 1 1/2 inches up to 3 inches I think? Seems that I remember S/S springs raise the back of the car up around 2-4 inches?

Im running 2" blocks on my 68 Barracuda with the 2800lb S/S springs. Launching at 5000rpm with a stick at the track. Holding up good so far. I guess it depends on what size tires your running. Im running a 28" tall tire and it put the rear of the car almost level with the front...which is damn near stock height

Thanks...that's the kind of info I was looking for...