The current front sight appears to be a current Recknagel product or it could be an early version of similar design. The hole in the rib may have been drilled to remove a loose piece of solder rattling around in there. I once had a W&C Scott with a rattle that drove me nuts. I would simply drill and tap and install a small metric setscrew for the hole in the rib. I would also put some light oil in the hole first to prevent corrosion inside the rib. I'd be willing to bet a lot of change that the recoil pad is aftermarket.
