Hi,
You didn't mention the drive system or locations. Is this going to be a belt drive w/o suspension? Is the motor going to be mounted on the chassis opposite the arm? If so, motor vibrations being transmitted to the arm is a consideration. Maybe you're going to mount the motor on a separate pod? I'm guessing that you have a better idea of what you're building then we do at this point. Some people mount the arm in a separate pod.
Your mention of a plinth has me confused. I was assuming that you were referring to the Micro Siki 1000, 1500 etc or the Clearaudio w/o plinths. Could you fill us in?
neo