OE Gas cap
I've done exactly as Dan recommended , back in the 90's for my '72 Dart and '73 Duster .
The O.E.M. handles almost fir exactly , but their mounting holes are off just a bit . While I've not tried it , one could probably elongate the mounting holes in the new cap , and retrofit the o.e.m. handle to the new cap , for a 100% stock appearance .