My K5 had a 3" body lift when I got it. Was going to take it off but never got around to it. The rear 4 lift blocks poked through the floor, so now the rear sags 3". I'm pretty sure the mount behind the drivers seat is starting to come through too. Now I'm not saying this will happen to yours (mine is very rusty), I'm just letting you know that it happend to mine.
When I swap the pickup cab onto the frame, I probably won't use a body lift. Maybe a 1". But that would only be because I plan to run a 40" tire with stock 52" springs and a zero rate up front. If I can't get it all in there, I'll run a small body lift.