Mounting a Rega RB300 into a Roksan Radius 5

Bought a REGA RB300 tonearm and a Roksan Radius 5. The hole in the Roksan is slightly, smaller than the pillar of the tonearm. Any suggestion from an AudioGoner that encountered similar problem. Suggestions on avoiding forcing the tonearm thru the board?
First, was the hole drilled for the Rega, or for a Rega mount?
If the hole was drilled for some other design arm, the geometry may be incorrect for the Rega.
Just a heads up. Good luck.