i saw this and thought this is the best place holder for those reflectors i've seen ~ but i am not sure if it is the right diameter ~
take a peek and see~ cgi.ebay.com/ebaymotors/NOS-VINTAGE-60s-RED-LICENSE-PLATE-FASTENER-REFLECTORS-/190519118651?pt=Vintage_Car_Truck_Parts_Accessories&hash=item2c5bd30b3b
just thot it might help/be useful
cheers~