I just got my '68 tach back (which I'm happy with) from the outfit suggested below. I did not have any "cosmetics" done, but I had lots of conversations with the guy, including dash 'renewal' services (which they do). Those chats, and the details on their web page led me to believe that it would be the place I would go to if I ever needed a cosmetic upgrade.
Here are the details: Auto Instruments (in SW Virginia), ph no. (276) 647-5550, ask for Gentry...and for what it's worth, tell him I sent you (Bill Hinkley) and refer to my '68 Impala tach repair.
Just a thought...