Best way to get a flip top gas cap on a dart

Anybody ever put a charger one with the trim ring on top of the quater like the chargers had? Maybe fab a recessed spot to get the trim ring to sit flush and you'd have to fab or modify a filler neck. I'd like to see one like this as I'm thinkin that might be how I'll do it if I put a flip top on a car.

Why not find a charger in a junkyard(if you can) and get the top of the 1/4 and graft it in