@rossb , Excuse me, all 9" Pro-Ject and Rega arms have a spindle to pivot spec of 222 mm. I even think the hole is the same size but I'm not sure of that.
MCMVMX , look for a used Rega arm. They are around. If you took the Pro Ject arm apart you should be easily able to put a Rega arm on.
Hang in there,
Mike