For your Plinth, if it allows, there is a not too expensive treatment that can be an concealed addition, where there is 2" Diameter Holes x 1" Drilled into the underside and fill the holes progressively in depth with Newplast Modellers Putty. Newplast has exceptional damping properties and should work very well in conjunction with the energy dissipation offered by the Butchers Block, 1/4" - 1" in depth should be more than enough to discover the attenuation that most suits ones tastes.
The Spacing between the Holes will be approx’ 1". This as a method is commonly seen on a Idler Drive Plinths both Professional Designs and DIY , but usually other materials are used to fill the holes, i.e, Lead Shot, Oil Soaked Lead Shot, Sand, Oil Sand, Rice.
The above is Old Skool and has been Superseded.
To get with the modern approach the use of a Resin Impregnated Densified Wood as the methodology is the one getting the most success and demanding the super high Plinth Prices from Professional Producers.
The other point of interest is that it is not Idler Drive TT’s alone benefitting from the use of Densified Wood as a Plinth Material, there are now well known Branded TT’s with it utilised as an important material for the Damping Dissipation values it offers.
The good news is that Densified Woods such as Permali and Panzerholz are not expensive to Source. If a design for a Top Plate for the Plinth can be foreseen, it should be possible to have a P’mali - P’holz Board as the Plinth and using the Butchers Block as a Sub-Plinth. Of the new Plinth dimension is oversized to the Butchers Block, Side Panels could be attached and the whole of the Structure is then Veneered.
This as a idea, can be found with a search on Google, there are a selection of very similar projects undertaken to be found.
Also important not to overlook the idea of a Speed Controller they are Transformative for a ID, and once experienced, I don’t know of any who wished to revert to no SC in use.
The link has a sensible discussion on approaches to a ID Plinth Design.