You have gotten some good suggestions for filling the screw holes. However, you really might want to reconsider leaving the holes where they are. You might not think they look good where they are, but they are in the mechanically best location to pull the plate up tight against the butt. It is pretty much where I put mine. I just need to make sure the toe screw is far enough from the toe and push rod for the patch box release. As to the heel extension, I put the screw behind any transitional file (like a wedding band) work between the heel and the comb. If you don't have anything like that, there is no reason not to put the screw right up at the end of the heel extension. I am sure the holes where put where they were for the most practical of purposes.