Origin Live Silver MK3A on Basis 1400

I currently have a Basis 1400 TT with a Rega RB250 (Basis modified). I'm looking to upgrade the Rega to an OL Silver MK3A.

However, I'm unsure whether it would be compatible given the usual issue with Basis TTs having a smooth bore for the tonearm to fit it.

Anyone have any experience with any current OL arms here?

Do I need a sleeve on the threads of the OL or is it a drop-in replacement for the Rega?

Any advice appreciated.
I have the latest Origin Live Enterprise-C arm on my Nottingham Dais, and it mounts in Nottingham's available Rega collet. There are no threads on the collet and it works out fine. The current Origin Live arms have built in VTA adjusters that allow you to set the height of the arm in a standard Rega size mounting hole. You should confirm this with your OL dealer to be sure the arm you are considering has similar compatibility with your Basis Rega arm mount. Hope this helps!
Thanks Bill, that's useful. How is your arm held firm without any threads. Does it just fit very tightly into the collet and the collet tightly into the TT.

I have emailed both OL and Basis for advice without response.

Regrettably, even though I'm in the UK the OL dealer network is very small. My nearest dealer is a substantial distance from me.
I didn't know that you were in the UK, but I would think that Mark Baker at OL would be best to address your concerns. The Nottingham collet allows you to clamp the arm at any desired height, but the current OL arms have a threaded VTA adjuster that allows you to securely set the desired height. The outside diameter of the VTA adjuster fits in a standard Rega mounting hole.