In case anybody is doing an automatic to manual swap here are a few pics of the location of the reverse light. Dash is out of a 76 dart custom. Pics of the micrometer are the hole size dimensions.
That may have been added after the fact. I got dimensions off a factory 4 speed car for mine. Its actually mounted lower than that. Not correct for a 67-68, but I am putting in a Hurst, and it doesnt have a reverse lockout, so I figured it would be appropriate.