Its going to be too hard to measure off of that because it's a curved surface that pivots, I would move the indicator over to the top of the valve retainer for more accurate results, keeping it parallel with the valve stem. Also, with the hydraulic lifters you may have issues with the plunger giving you false readings. You may have to tighten the rocker down a little at a time with the indicator on the valve retainer until it moves, then move it back so it's exactly at zero with the lifter in the closed position. This should preload lifter and reduce that chance. You are talking thousands of an inch makes a large measurement difference since the crank turns twice as fast as the cam, so you have to be very critical with this. Just be sure to readjust the rocker back to normal when you are done, before you run the engine.
Also, where is your wire pointer for the wheel? You can make one of a coat hanger that you can bend to zero after you set it to true TDC.
One other thing, once you find true TDC for number one, make a new mark on your timing tab if it's not dead on, I find many times they are a couple degrees off.