A Basis Vector tonearm has the same mounting distance and will drop in the same mounting hole if your Rega is a single hole mount. It will be a very significant upgrade from your Rega tonearm. you will not be disappointed. They occasionally show up used.
Tone arm upgrade
I'm currently using a Rega RB300 modded tonearm ( aftermarket wiring harness and counterweight). I'd like to consider a step up, have been keeping my eye open for a good condition used Linn Itok arm. Is this the right path or in the $1~$2k price range is I there another good alternative?