I have a 68 400HO coupe with two tone paint (originally on build sheet)the car is currently in primer. The bottom was Mayfair Maize and the top Cameo Ivory and the gut is deluxe parchment-pearl. I plan on redoing her in a few years and I imagine I will need that trim, but will have to settle for the vinyl top stainless trim pieces. I don't think it is too uncommon, but that combo you have seems unique since it calls for a burgubdy roof, usually- you see white or black since the idea was that it look like a ragtop car.
Like you, even if I wanted to go back with the two tone paint, finding the correct trim piece would probably be next to impossible, and even if you did find one, you just know the guy selling it would think it's made of unobtainium.