@ddriveman I do not own the SP10 R, it is a friends, this individual was initially a user of a Linn LP 12 that has many Upgrades included. They purchased the SP10 R after being demonstrated my modified SP10 MkII.
As for the TA Selection they were suppled a range of TA's to trial with the New un-plinthed TT, mounting TA's on a Standalone Arm Pod.
I even loaned a SME IV to be trialed with other TA's, the 12" Glanz was the one that made the biggest impression.
This TT, is mounted in a Solid Aluminium Plinth produced by a machine shop to the owners dimensions, the TA remains mounted on a Pod.
My suggestion for you as a Plinth Material is to investigate the use of a Densified Wood such as, 'Panzerholz' or 'Permali'. To attain knowledge of this material early on in your planning will give a good footing for the future plans. I know from personal experience how valuable this Plinth type is a addition to a DD, especially the Technics SP10 design.