When I was at the 85 Nations in MI, I was cruising through the hotel parking lots in my 65 Dart GT 'vert when a lady came out waving and made me stop. She said she had a 65 Dart hardtop the same color back in Canada and my 65 was the only one she'd seen there. Said if I was ever up in the area, please stop by and see her car. Since I was making a side trip through Toronto on the way back to VA, I did stop and took a look at her GT hardtop. It had a metal sliding sunroof in it and she insisted it was factory installed. Whoever installed it did a great job and it looked factory even on the inside. Seems to me that if the donor sunroof had the same profile as the Valiant (or the Dart I saw), It ought to be fairly easy.