Come on now, let's compare apples with apples and oranges with oranges. We are talking about 111 coupes and you're talking about 126 cars. They're not the same and the comparison isn't even valid.
From what I remember 1966 model year cars had no real differences as far as engine out put or design from Euro to USA editions. Later on there are differences but that didn't start until the early 1970's with some changes as early as 1969.