The LA 318 didn't come out until the 1967 MY in the US.
Over the years, I've owned a pair of '66 Darts: a 273-2v, 3-speed, 270 HT; and a 273-4v, auto, GT HT. Your project reminds me of the GT. The only things I didn't take off of that car were the backlight and the windshield. It turned out well.
