Need help on centerlining my cam.

Using the retainer you have to use a solid body lifter or a modified hydraulic (locked solid). Otherwise the lifter will collapse under the weight of the spring, and the rate of collapse will not be consistant enough for measuring by the .001". If the collapse is not consistant, the measurement will be off by a bit. It only takes a few thousanths to change the degree reading significantly. BTW, like Terry said, you'll be amazed at how much less lift the valve actually gets after you get thru the poor pushrod angles and rocker ratio issues. In a small block LA or Magnum, you may loose .020 of lift just with pushrod angle because it's so bad.