That nearly hidden line you mention goes to the nipple like the one shown capped in your '67 photo above. From the factory, the vacuum line connected there fed the air cleaner's flapper door vacuum control. Make sure your flapper actually opens and closes with vacuum and temperature; it's a common failure. Fail open is okay as long as there is no vacuum leak; fail closed will cause a constant rich condition.
The vacuum lines and TVS are incorrect for that engine and the valley pan is on backwards; it is a nice pic of the air cleaner, though!
Vikki 1969 Goldenrod Yellow / black 400 convertible numbers matching
