Just for fun:
1. Changing the rocker height, stem height, lash cap etc. all change the geometry - they are not adjustments.
2. There is no "correct" valve length, only correct for a specific geo method (Miller, etc.), rocker ratio, and lobe height.
3. The position of the roller on the stem with correct geo only 1/32" from the edge will do less damage than centered by trashing the geo - which is what is advised several times here.
What to do:
STOP.
Set the geometry using the parts you have now.
Assuming mid-lift is your target, the roller should begin on the stem edge closest to the shaft side, roll across the stem to center @ 25% lift, continue across to 50% lift at the far side, stop, and reverse, passing through 75% on center and reaching full lift at the same position as closed.
If it does that, and the roller is too close to the near edge, you need to shorten both the stands and valves to separate them by the difference between the vertical stand position and stem axis. Too close to the far edge: raise both.
. 
and not miss any more of the season than I have to.
) wants.