Definately a L36, 390hp car. Yes, it would have been a Turbo 400 backing it up. As previously stated it would not have come with a dual snorkle air cleaner. Only L72's (427/425hp) came with them in 1966. Also the valve covers would have been painted. Even '66 Vettes had painted ones. Lots of people like to dress them up. Doesn't chrome make them more aerodynamic?!?!
Anyway, the car could be a lot worse. I think it would be great to restore. You don't see them too often. Here's another website you should check out. I've been a member with them 10+ years.
web page
More Later. Have fun.