71 Demon 340 Gas Cap??

Hi,

I am having a major problem locating the proper fitting gas cap?? My car has the 4 vent tube gas tank which means it should have the non vented cap..I had the vented cap which is to deep and spins...I purchased a new one from yearOne which states 67-76 A-Body non vented but, the cap stops are 1/2" deep and it also spins when in place? Plus the prongs are to wide?? I believe the depth between the seal and prongs should be 1/4"

Does anybody have or know the correct cap or where to purchase?
Please I am desperate!! My body guy is done and needs to paint the cap and apply the stripe piece on cap.....

Thanks, Steven
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