Just seeing this thread for the first time. Amazing work! All the suggestions have really improved the overall appearance of what was already a nice piece. The only thing that seems slightly 'off' to me is the eyes. As was previously mentioned, I dont know if its that the irises are a little too large, or the openings are a bit small, but I always remember Spock as having a decent amount of white surrounding his eyes.
Looking back at the reference pics you have in post #62, the overall face is of a 'younger' film Spock (STTMP or WOK), but the sculpt seems to have his heavy eyelids as in The Undiscovered Country. I think that's why it seems just slightly 'off' to me. Aside from that one minor thing, It's incredible. Love the idea of the sound chip too!