They are effective at lowering a car. As 1 Wild R/T points out, the shock doesn't need to be changed ( the A body shock is the same length as an E body shock too, but truck shocks are longer) and it can lead to spring wrap issues if you drag race on prepared tracks with sticky tires using stock springs, but even that can be overcome with the proper parts.
If using lowering blocks, I'd suggest using a billet or extruded version instead of a cast version. Billet and extrusion will bend if shock loaded whereas cast will cracked and potentially come apart. That means no cheapy part store versions. Pick them up form Speedway Motors or another reputable vendor.
