Hello KOF. I have a new Tiger Paw Akula subchassis with a new Linn armboard on it for sale for very reasonable, if interested.
I've had a "full blown" LP12 project for many years with all the upgrades; machined subchassis, thicker top plate, DC motor, Ekos and Akiva, even a custom wood plinth. We put a new Cirkus on it as well, though my tt expert (started with Linn and Naim in the early 80's) says some prefer the old style. In fact we sold the original bearing for pretty good $ actually. But the overhauled tt does sound fabulous; very high resolution.
I also started with an LP12/Naim system in the mid 80's, so am pretty familiar with it. Thankfully I never let vinyl go, even when it was "dead".. ;)
Sorry, don't know about the shims required to install onto a stock subchassis. Might call an LP12 dealer (Audio Concepts?).
TK