Ok, you would probably want a 67 RO/WO style scoop, direct bolt on to your 66. There are a few sources.
In steel (which is what originals were) If you don't mind waiting I believe you can still have Domingo in Lima Peru get have his body guy to make one for you
www.playbackauto.com. These are the same ones I used to sell for $799.00, very high quality, I believe they are more $ now.
Next source would be Joe Coal "The Tynman" in Michigan.E-mail Joe at or call 419.215.7270 again, hand made, high quality, about $1,500.00, usually about 60 days waiting time based on what some of his customers told me. I don't have his contact info. handy.
Next would be Kramers, his are very nice fiberglass replicas, under $300.00, currently on back order.
All of the above bolt on.