gas cap alignment on 65 barracuda

The stock one has a straight bar that should be horizontal when installed and tight.

Yes. And when the cars were sold, they had painted gas caps. But if you lost your original and went to the dealer to get a replacement, you got a stainless steel cap with a chrome bar - I'm guessing it was so the dealer wouldn't have to stock caps in all the available colors, or have to paint the cap body color. Just screw on the shiny cap and go.