reasonable probabilities. While clocking may seem non effective it is still worth a try since your options are slim. The mounts are the same. What about tire balance what type have you done like road force balancing? High speed vibs could be due to tires. What is condition of tires and rims? Have you checked the rims for lateral runout to be in spec. What about radial runout for the rim tire combination? Have the tires and rims ever been match mounted to reduce radial runout and provide foe a better balance job?
It could still be your 1 piece DS dynamic balance. The reason Nissan did the 2 piece was to get better dynamic balance out of the DS and related components.
