Good Luck on finding your GTS. Closest on crazy color combo's I know of is a '69 GTS thats Gold with a green vinyl top and gold interior and V88 stripe delete.
I was checking the numbers in my '73 Duster and the Engine is a '68 340 that was transplated along with its matching trans it looks like.
Cast date on motor is 6-2-67. If these have a vin are they on the rail like the later ones or??