pinion help

okay i have been reading and looking all over the place and still came out conf...now my ?? to help me clear my mind on this is my trans is at 4 on the finder and rear is at 3 on the finder when i cut the perchs off i need to roll it down to 4 and then about 2/3 more???i know i may sound dumb but would like to get it right the 1st time...also from a little help from another site i was told to just nubolt back of springs and allow the rear to come down then cut them of and clean up spots on houseing..then put the springs back up in the back with the new perchs take my measurement and tack.....hows this sound to you guys......also i took my measurements with driver in the seat...