6x8.5 is better, I think... since the 35mm negative dimensions have a 1.5:1 ratio (36:24=1.5:1). Original 6R has 8:6=1.33:1 ratio; some of your neg may be cut off? Not sure about CCD ratio.
6R IS 6 x 8. And film is 2:3. That's why if you look carefully at your negatives and prints, the sides on the prints are gone. Cos the sides are cropped off.