68 Barracuda What Goes Here?

Hi All! I have this 68 Barracuda with a Slant Six. To say the car is not complete would be an understatement :) I am currently taking stock and acquiring missing parts. I found this hole above and to the right of the Brake Master Cylinder and cannot figure out what is supposed to go there. Anybody know?

Also just below the hole there is something that kind of looks like a relay? Anybody know what it is for as well?