Sure- try it. Don't know how similar the black Aristons are to red Konis that were optional on Euro GTS & GTS/Gr-3s. Original '71 Konis had adjustable damping if yours were too soft or hard. We used to adjust the front damping at one click and the heavier loaded rears at two clicks. Three clicks would loosen your fillings. Note also the fronts and rear shocks have 1 digit different stamped numbers and the long rubber bumpers go in front while the short ones are for the rears. I believe the main springs were of different strengths, too.
To adjust original red Konis, you had to remove the shocks from the car. Drive a roll pin out and unscrew the shock mounting eye, then completely collapse the shock rod. At the bottom of the rod inside the shock body was a fork that engaged the adjusting damper rings. With the shock mounting eye in place, the rod won't go in far enough to engage the adjustments.
With pliers, rotate the fully collapsed shock rod in either direction until you feel a click. There are 3 positions. Test by moving the shock rod in the body up/down by hand to verify where your shocks are- the damping stiffness for the 3 settings is quite apparent. Koni used to include a 3-pg illustrated brochure with their new shocks, which were guaranteed for life if you kept the receipt. Official Koni-America rebuilders used to be in Kentucky but 50+ years is a LONG time....