Don,
Jake and I did it with a cut out from a 68 qtr. Not the adapter look your looking for pics of, but like @66jim says - looks factory. We should have cut it in up higher on the qtr , as opposed to the original 65 location.
That does look like a factory install. I have a pair of gas cap recessed panels - one from a 71 Charllenger and one from a 69 Charger. I’d hate to start modifying the quarter on the wagon as I’m within a couple of days for paint!
