Getting the geometry correct on roller rocker position?

You need to put shims under the shaft. That will raise the shaft up obviously you'll like you're thinking you'll need to unscrew the Adjusters, but it'll take up the slack very quickly it won't put it out more than a couple more threads if things get bad and that's not bad. Yes ideally you want about two threads.
Edit: yes I have two threads on mine, but if I had four I wouldn't be freaking out at all. But if I had the adjusters bottomed out with a half inch, I'd be holding my breath...