Building a fence down towards the neighbor. The posts should be as close to the L concrete support as possible, so I chose to drill 20 mm holes in the concrete for attaching these post shoes. They sit fairly securely when inserted into the holes, but I want to affix them more securely—is stone adhesive suitable for this? I assume the holes are too small for casting since the post shoe has almost the same diameter. How do I best fasten the post (70x70) in the shoe? Only a larger hole in the post shoe, is it best with some form of through-bolt or better with a short lag screw from each side?