I don't see it myself. 67 rods just have a different angle at the end where they bolt to the lower arm. If you look at the catalogs, you'll also see the lower arms are also unique to the 67. Solely because the two bolt holes in each are in slightly different locations to accomodate the strut rod.
Better or worse? I don't really think so. If you have worries or doubts you can just replace the rods and arms both with new ones for a "68". As long as you replace them together they are a direct fit. 67 rods WON'T fit 68 arms, and vice-versa. Nor is it practical to modify either one to fit the other year. ( I tried that once, don't ask)