A '71 would have the part number on the back of the tach of 5657407 for LS6. You are right on the color of the lettering!
Sell it on ebay, thats the best bet. Start low, say $99 for example, (save $$ on listing fee's) and set a reserve of what you would like to get, let the buyers set the price. There's million's of people shopping ebay at any one time.
I have seen the whole dash assembly sell for 200-400 at swap meets.