Most low profile gas blocks are going to be under a FF rail system so they aren't going to get beat back and forth....no need to drill.  Just tighten and you should be good.

If you are super anal, tighten it down make sure it's aligned properly (shoot it if need be) and uninstall.  You should see the screw marks from the set screws.  Drill tiny dimples where the screw marks are and reinstall.

If it's me, I'd just tighten it and forget it.

Good luck