Here is the finished frog (well, almost, still need to finish shaping the grip and apply finish). The 3/4” (thick) aluminum mouth block has been screwed and glued (epoxy) to the infill. The frog is held to the sole with three 1/4” x 20tpi stainless screws (pan head because they are low profile (the tops are below the wood) and have a wide bearing surface). 1/2” (diameter) access holes have been drilled in the infill to allow for adjusting the frog.
It works really well. The mount is solid, easy to adjust and self aligning. This last [unexpected] benefit has turned out to be really nice as the two surfaces of my iron are ever so slightly out of parallel. The frog has enough slop that I can get perfect contact between the lever cap, iron and frog/bed. While I am worried about wood movement causing misalignment, I’m [currently] thinking it won’t be much of a problem. We’ll see.