[427 S/O]

I didn't install a horn!, just pat the throttle......On the vents I cut two 1/8" aluminum plates the same size as the top of the foot boxes, cut a 3" hole in the plates and welded in a 3"X3" aluminum tube that sticks up into the engine compartment, cut a 3 1/8"round piece of aluminum, bolted on a small hinge and made a flapper for inside the foot box with a cable pull, picked up two 6'X3" vent hoses from NAPA and ran them from the front air vents. A little labor intensive but with hot Georgia summers, you need them.
The short distance the hoses run from the wheel well to the foot box, you will need to insulate, I used the aluminum covered bubble wrap.