Triplanar Vll onto JA Michell gyrodec

Hello all

I just recieved my Triplanar and ZYX Universe from Mehran.

My JA Michell GyroDec has a round metal armboard / plinth?. It is drilled for the Zeta / Ittok tonearms. I have moved the round mounting plinth to all three possible positions. None of them line up with the mounting jig supplied with the Triplanar tonearm.

I believe I have a number of options:
Order a proper JA Michell metal plinth for Triplanar
Drill three holes into the original plinth
Make a plinth out of plywood or baltic birch
Any other options you all may have

My ultimate question is; what is the best possible material for a Triplanar armboard?

Yes, a new Turntable is in the far future.
Thank you Doug. I have a piece of Oak door jam here. I will make a temporary armboard until I can get the cocobolo.