I do not think you have the correct battery hold-down. That looks like a '66-'69 item. The '60-'65 item is similar but not the same; all the '60-'65 original A-body battery hold-downs I've seen have been in accord with this, this, and this; TTBOMK both J-bolts have been black phosphate and not silver cad. Silver cad on the wing nuts and washers, though.