Not Mopar but followed me home anyway-----

Nice find! Especially with the 4 speed, likely pretty rare in a Comet, I didn't think the Cyclone package was available until 67, but I could be wrong. I have seen a dual quad sbf before, but it's not common. 289's were available into 1968, I had a 68 Fairlane 500 with a 289 2V, and know of several 68 Mustangs that were born with 289s. Easy to make 400+ HP with a well built sbf, good luck and keep us posted.