My Coronet 500 came with a 426 Street Wedge. That was the top of the line engine option in 1965 for those cars.
The engine isn't too wild but if you look close the valve covers are made from billet. That is a clue. If you go look at the Duster engine pictures you'll see the same billet valve covers. I made a few sets of those covers and used them on some special projects.