Here is another survivor pic showing the tach wire coming out of the correct area as well as the stud/nut out of the hole you are asking about.

5979955-survivor.jpg (151 downloads)
'69 Hemi Charger 500, ‘70 U code Challenger R/T
(These and a bunch others at www.dkowal426.com)

P.J. O'Rouke: "The old car ran perfectly, right up until it didn't."