Not sure about the match. It must be non-vented to work for me. Did your Swinger have ECS (evaporation control system)? If yes, then it would be a vented type cap.
Is it chrome or Rallye Red?
Also, I think the cap should be 3 1/4" O.D. and the under side section that slips into the gas tank filler neck is 1 3/8" O.D.
