This is the trickiest battery plate to install. The reason is the fuel tank is permanently secured to the frame. The holes for the rivet and the lock screw need to be precisely 1 and 15/16" on center from each other. As mentioned in the article, the dimple in the battery plate should rest in the center of the large battery hole when it's closed.
Before you drill the two holes, mark their positions and re-check the battery plate's position on the fuel tank. When drilling, make sure you hold the drill straight so the hole is 90-degrees into the diecast. Obviously, a drill-press would be ideal, but who has one?
1/8 drill bit for the rivet. Start with a 3/32 bit for the lock screw. Then tap the hole with a 5/16 self-tapping screw. You'll need to use some elbow grease and maybe some oil. Then the lock screw should go in without much resistance. Do not over tighten it because the threads stop before the head.
Parts diagram on left. Above is wiring diagram.