You are using self-aligning rocker arms aren't you?
Pic #1 shows at least 1 rocker that isnt centered properly and would cause issues if it was run.
Vortec heads are designed to use a self-aligning rocker arm as they dont use guideplates. You either need guideplates, or self-aligning rocker arms, but NEVER both at the same time.
If you look at the underside of the rocker arm at the arear that sets above the valvestem, there should be 2 raised areas that ride on either side of teh valvestem thus keeping the rocker arm centered on the valve.
Here is a self-aligning rocker arm, if your rocker arms dont look like this, you need to get a set of them.
Here is a self-alining roller rocker arm, it uses 2 vertcal washers to self-align the rocker arm
AP72, just blow up the pic. I had to zoom in quite a bit to see, but it was too blurry to see the self-aligning marks.
peace
Hog