Flip Gas Cap Conversion?

go with the shelby style aluminum cap from a viper, cobra and a bunch of other cars. i always toyed with the idea of recessing one of those into the flat top of the quarter of my 69 dart. if you do it, you have to recess it just like the factory did to the barracuda and other cars wi ththe flip top caps or it will look like you just slapped it on there.