Need help with Ariston RD 90

I doubt if any would be available after all this time. I was an Ariston dealer but don't remember a speed controller. If a current one like the Project or VPI would work [and I have no idea if they would] that would probably be the best bet. I use the VPI in my demo system and it is good but expensive. The older series should also work and be a fraction of the cost bought used. But I would check out the Project as they appear to offer good value for money.