i chopped the top of the frame for two reasons. first being when i did my 3 link i mounted my lowers a fraction of an inch from the ground, so cutting the bottom of the frame would have put my lower links into the ground, lol. reason two is then you have to Z the frame that much more to lay out if you cut the bottom of the frame off. looks like about 1.25" would lay rocker. i do have a c20 so that may be different for you. ive also read that you can drop the body about an 1" without modifying the frame.
ignore the crappy welds, rear is getting redone
hope that helps, let me know if you need anything else