The other piece of the puzzle is vapor recovery for the gas tank. I should do a write-up on that as well.
Back when these cars were new a detached garage was the norm. Very few were attached to the house, and I don't recall ever seeing a basement garage. These car polluted more sitting in the garage than a modern car does cruising down the highway.
The earliest emission controls eliminated the direct atmospheric vent from the carburetor (which the '64 had). The next step was to vent the gas tank through a carbon canister.