I ended up buying a universal mount by CZ customs. They claim that they don't have a mount for the 407k/507k however I think they make that claimbecause the metal nubs that they include with the dovetail mounts need to be filed, sanded, grinded down. It seems to fit well though the Holosun sits a little forward in the universal plate. The plate is also very slightly angled downward so I would believe that that would solve for the vertical adjustment issue you have since I was able to easily zero my optic.
https://czcustom.com/multi-sight-base-75-st-black.html
