I got a very similar looking kit with the 70-style repop grille that I put on my 72 Swinger. It also didn't come with a diagram but I do remember that the installation went very smoothly and that it was pretty obvious where all the screws went. If I remember correctly, that longer screw went in the upper outsides of the headlight surround.
Sorry -- Not a ton of help I know, but just start installing it and it will all be clear which hardware goes where.